Overview and Maintenanaces of HVAC system

1
THE GUIDED TOOL FOR
OVERVIEW & MAINTANENCES
OF CENTRALISED AIR
CONDITIONING SYSTEM

2
INDEX
1. Introduction to Air conditioning systems
2. Chiller plant room
a. Chilled water central air conditioning systems
b. Chilled central air conditioners
c. Water pumps
3. Cooling tower
4. Air Handling Units
5. Grills low side
APPENDIX
Conclusion

3
CHAPTER 1
INTRODUCTION TO AIR CONDITIONING SYSTEMS

4
INTRODUCTION TO AIR CONDITIONING SYSTEMS
Air conditioning is a combined process that performs many functions simultaneously. It
conditions the air, transports it, and introduces it to the conditioned space. It provides heating
and cooling from its central plant or rooftop units. It also controls and maintains the
temperature, humidity, air movement, air cleanliness, sound level, and pressure differential in a
space within predetermined limits for the comfort and health of the occupants of the
conditioned space or for the purpose of product processing.
The term HVAC&R is an abbreviation of heating, ventilating, air conditioning, and refrigerating.
The combination of processes in this commonly adopted term is equivalent to the current
definition of air conditioning. Because all these individual component processes were
developed prior to the more complete concept of air conditioning, the term HVAC&R is often
used by the industry.
AIR CONDITIONING
An air conditioning, or HVAC&R, system is composed of components and equipment arranged
in sequence to condition the air, to transport it to the conditioned space, and to control the
indoor environmental parameters of a specific space within required limits.
Most air conditioning systems perform the following functions:
1. Provide the cooling and heating energy required
2. Condition the supply air, that is, heat or cool, humidify or dehumidify, clean and purify, and
Attenuate any objectionable noise produced by the HVAC&R equipment
3. Distribute the conditioned air, containing sufficient outdoor air, to the conditioned space
4. Control and maintain the indoor environmental parameters such as temperature, humidity,
Cleanliness, air movement, sound level, and pressure differential between the conditioned
space and surroundings within predetermined limits
Parameters such as the size and the occupancy of the conditioned space, the indoor
environmental parameters to be controlled, the quality and the effectiveness of control, and
the cost involved determine the various types and arrangements of components used to
provide appropriate characteristics.
Air conditioning systems can be classified according to their applications as
(1) Comfort air Conditioning systems
(2) Process air conditioning systems.

5
Assembly diagram:VAPOURCOMPRESSIONSYSTEM
damperductMakeuptank
Returnairdamper
supplygrillcoolingtowerexhaustfan
outletline
rawwater
inletline
airhandlingunit
coolingtower
expansionDevicerainwater
outletinlet
liquidline
evaporatoroutlet
reciever
dischargeline
PressureNossil
inlet
condenseroutlet
compressor
boostrpump
condenserpump
inlet
Domestictank
pleum
primarypump
secondarypump

6
Energy Wheel: The energy wheel turns and absorbs the heat and moisture from the outdoor air
that comes into the AHU through the duct which supplies the outside air to the building. The
exhaust air (cooler and partly conditioned) which has to leave the building is first made to pass
through the energy recovery wheel. The moisture and heat absorbed by the energy recovery
wheel from the outdoor air from II is absorbed by the exhaust air which is cooler and partly
conditioned, thereby lowering the humidity and temperature of the outdoor air which is to be
passed over the cooling coils and then to conditioned space. Basically, an energy recovery
wheel utilizes the partially conditioned exhaust air leaving the building to condition the
incoming outside air. Other benefits of energy recovery wheels include removing moisture
from outdoor air which reduces or prevents moisture and humidity problems and it will also
reduce mechanical cooling in the summer.
An air system is sometimes called the air-handling system. The function of an air system is to
Condition, to transport, to distribute the conditioned, recirculating, outdoor, and exhaust air,
and to control the indoor environment according to requirements. The major components of an
air system are the air-handling units, supply/return ductwork, fan-powered boxes, space
diffusion devices, and exhaust systems. An air-handling unit (AHU) usually consists of supply
fan(s), filter(s), a cooling coil, a heating coil, a mixing box, and other accessories. It is the
primary equipment of the air system. An AHU conditions the outdoor/ recirculating air, supplies
the conditioned air to the conditioned space, and extracts the returned air from the space
through ductwork and space diffusion devices.
A fan-powered variable-air-volume (VAV) box, often abbreviated as fan-powered box, employs
a small fan with or without a heating coil. It draws the return air from the ceiling plenum, mixes
it with the conditioned air from the air-handling unit, and supplies the mixture to the
conditioned space. Space diffusion devices include slot diffusers mounted in the suspended
ceiling; their purpose is to distribute the conditioned air evenly over the entire space according
to requirements. The return air enters the ceiling plenum through many scattered return slots.
Exhaust systems have exhaust fan(s) and ductwork to exhaust air from the lavatories,
mechanical rooms, and electrical rooms.
For study purpose we have taken the HVAC system of a large commercial building in a city like
Bangalore , India, which operates , water cooled operation of 3 nos 800 TR chillers, 3 nos 800
TR cooling tower and 25 nos of AHU’S which caters the need of 300 odd tenats and common
areas. The details are presented in the subsequent chapters below. We start with common
problems faced by maintenance personnel.
Issues in HVAC System –Observation queries raised by Facility team
 Surging problems: Whenever all 3 chillers are running there is a surge problem and chiller trips
automatically and unable to avoid it.
 Maintaining condenser approach and range up to 4-5 is practically difficult.
 Cooling tower capacity to be analysed on its position and capacities. Its present efficiency.

7
 Whether we can maintain the water hardness less than 200 ppm and TDS less than 1500 ppm
as per chiller standards after using the chemicals (anti scalant, Biocides).
 The condenser water flow rate (using ultrasonic flow meter), condenser pressure are adequate
or not.
 Condition of fills in the cooling tower are good or not ?
 Whether with the present load status can the plant run one sequence chiller-cooling tower-
condenser pump.
 Commenting on overall healthiness of the cooling tower, its fan condition and all other
parameters.
If conditions of occupancy not met
 If designed parameter of chilled water and flow rate is supplied properly by Developer to the
tenant Ceiling mounted /Floor mounted AHU the scope would end since the Internal CSU unit is
self-supplied by end user/ tenant.
 Hence its essential shop wise analyze the problem where ever issues are raised whether the
CSU units are selected for adequate TR and appropriate coil sizing and thermostats of two way
valves functional etc. needs to be conducted case wise when issues are raised.
 Above false ceiling sealing to be cross checked for any mixing of zones above false ceiling etc.
General Observation
Thermometers reading across the chiller and the chiller inbuilt sensors both are showing
different temperatures. Both needs to be checked for accuracy and the faulty set to be
calibrated.

8
CHAPTER 2
CHILLER PLANT ROOM

9
CHILLER PLANT ROOM
A. Chilled Water Central Air Conditioning Plants
The chilled water types of central air conditioning plants are installed in the place where whole
large buildings, shopping mall, airport, hotel etc., comprising of several floors are to be air
conditioned. The plant room comprises of chiller units placed on civil foundations, primary,
secondary pumps for pumping water from and to the AHU’s respectively positioned in different
floors and condenser pumps for pumping water to and from cooling tower
In chilled water plants, the ordinary water or brine solution is chilled to very low temperatures
of about 6 to 8 degree Celsius by the refrigeration plant. This chilled water is pumped to various
floors of the building and its different parts. In each of these parts the air handling units are
installed, which comprise of the cooling coil, blower and the ducts. The chilled water flows
through the cooling coil. The blower absorbs return air from the air conditioned rooms that are
to be cooled via the ducts. This air passes over the cooling coil and gets cooled and is then
passed to the air conditioned space.
Chilled Central Air Conditioners
Various Parts of the Chilled Water Air Conditioning Plant
Chiller is the heart of HVAC system. As the name indicates it is the machine which chills water
and gives this chilled water further to units on low side. Chiller employs a gas usually termed as
refrigerant that is passed through various components, finally exchanges heat to the medium
(water or glycol) which carries this chillness to AHU, for cooling purpose or the equipment
where process chilled water is required.
Chiller is classified as water cooled or air cooled. Generally Air cooled chillers are available for
lower capacities (<500 TR). Air cooled chillers is devoid of cooling towers as the fans are part of
condenser unit itself. Air cooled units are used wherever capacities are less and where there is
a space constraint. Water cooled chillers on other hand are chillers of larger capacities (>500
TR) and which employs another unit called “cooling tower”. Individual standalone water cooled
chillers are available up to 5000TR. The size of chiller is based on its capacity or tonnage (TR). 1
ton is defined as the amount of heat required to bring down temperature of water by 1°C. A
100TR chiller has a 100 times capacity to bring down the temperature of water. Similarly an
800ton chiller has capacity 800 times to bring down the temperature of water.

12
Chiller description:
A chiller comprises basically of 4 components.
Compressor: A compressor compresses the refrigerant and pushes it to the condenser. The compressor
is classified depending on type of compression. Generally different compressors are screw type,
centrifugal type, scroll type, reciprocation type etc.
 Screw type utilizes screw elements to compress the gas. The gas is allowed to pass through the
screw profile, which is rotating on a common rotor and gas progresses it get compressed.
 Reciprocation type uses a piston cylinder arrangement. The piston pushes the gas and
compresses it.
 Centrifugal type uses a backward current impeller on a rotor. As the refrigerant passes through
the impeller its pressure increases and gets pushed forward to the condenser.
 Scroll type, as the refrigerant gets compressed, its pressure and temperature increases before
entering the condenser.
Condenser: condenser is the section of chiller where gaseous foam condensation takes place. The high
temperature refrigerant gets condensed and becomes liquid phase at the end of condensation. The
condenser usually consists of tube made of cu, where water passes through it and gas flows on the
opposite direction around its periphery. The mode of heat exchange is convection where there is no
physical contact and as the refrigerant and water traverses through opposite direction the refrigerant

13
gradually becomes cool and condensed, water eventually gains heat. The pressure of refrigerant is
maintained constant. The operating pressure is between 720-780 KPA for an 800TR chiller.
Expansion valve: It’s a float value where there is pressure drop of the refrigerant. The pressure drops
and the refrigerant regains its gaseous form.
Evaporator: The refrigerant travels through a shell and water returning from AHU travels through the
tube. Here too there is a heat exchange between the refrigerants and water. The water which is at high
temperature say 14°C up to 7°C gets pumped back to AHU. The PH scale diagram of a chiller is given
below indicating flow of refrigerant.
12 compression stage
23 condensation stage
34 Expansion stage
41 Evaporation stage
Refrigerents commonly called as gas used in chillers:
1) CFC’s (chloro flouro carbons)
R11, R12, R13,R14, R15 etc
2) HCFC’s (Hydro chloro flouro carbons)
R22, R123, R124, R141b, R142b
3) HFC’s (Hydro flouro carbons)
R32, R123, R134a, R143a, R142b
In modern day chillers HCFC’s are most commonly used refrigerant as the have ODP (Ozone depletion
potential) very minimal or zero. These refrigerants even in case of leak, escape to surroundings may not
cause depletion of ozone and protects it.
Let us take an example of a 800 TR chiller of a xxxx Brand make with all specs given below
1
2
3
4

14
CHILLER Calculations:
IKW =
Motor KW = V=voltage of 3 , I=Amps, Cos = power factor
Tonnage (TR) = ( )
IKW of chiller = 449/800=0.56
System IKW of 800TR chiller: Based on formulas mentioned above, the
IKW of chillers are calculated. Example below is the tabulated record of
a real time 800 TR chiller which is operational in a large commercial
building.

15
Chiller#1
Chiller#2
TIME Delta T( 'F) Tons
%
Efficiency Volts(V)
Load (
Amps) PF Motor KW IKW
% OF
COOLING
CAPACITY
KWH
consumption
9:00:00
10:00:00
11:00:00
12:00:00 9.9 747.45 93.43125 392.4 691.9 0.9 244.3514 0.3269134 95.36 407.8
13:00:00 9.9 747.45 93.43125 396.7 690 0.9 246.3507 0.3295882 94.5 397
14:00:00 9.18 693.09 86.63625 401.4 626.5 0.9 226.32939 0.3265512 86.5 440
15:00:00 9.54 720.27 90.03375 402 646 0.9 233.7228 0.3244933 89.1 401
16:00:00 9.54 720.27 90.03375 401 646 0.9 233.1414 0.3236861 91.8 406
17:00:00 9.36 706.68 88.335 397.9 661.9 0.9 237.03301 0.3354177 91.2 504
18:00:00 9.9 747.45 93.43125 395.7 691.9 0.9 246.40635 0.3296626 95 347
19:00:00 10.08 761.04 95.13 403.5 686.2 0.9 249.19353 0.3274382 94.3 438
20:00:00 9.54 720.27 90.03375 400.8 654 0.9 235.91088 0.3275312 91.2 448
21:00:00 9.9 747.45 93.43125 400 661.4 0.9 238.104 0.3185551 92.9 355
22:00:00 11.52 869.76 108.72 404 688.1 0.9 250.19316 0.2876577 95.8 282
23:00:00 8.5 641.75 80.21875 405 538.1 0.9 196.13745 0.3056291 74.8 511
4936.8
TIME
Delta T ( 'F) Tons
Efficiency
of
Tonnage (
%)
Volt (V) I (Amps) PF Motor KW IKW % OF
COOLING
CAPACITY
CHILLER kW from
Conserv Meter
9:00:00
10:00:00
11:00:00
12:00:00 11.34 791.91 98.98875 401 695.6 0.9 251.04204 0.3170083 95.6
13:00:00 11.16 779.34 97.4175 402 688.1 0.9 248.95458 0.3194428 95.6
14:00:00 10.62 741.63 92.70375 400 658 0.9 236.88 0.3194046 89.1
15:00:00 10.48 731.85333 91.481667 398 611 0.9 218.8602 0.2990493 83
16:00:00 9.54 666.21 83.27625 399 583 0.9 209.3553 0.3142482 80
17:00:00 9.72 678.78 84.8475 401 598 0.9 215.8182 0.3179501 83.9
18:00:00 9.72 678.78 84.8475 396 596 0.9 212.4144 0.3129356 81.4
19:00:00 10.08 703.92 87.99 396 609 0.9 217.0476 0.3083413 86.2
20:00:00 10.3 719.28333 89.910417 396 609 0.9 217.0476 0.3017554 83.9
21:00:00 11.7 817.05 102.13125 399 678.1 0.9 243.50571 0.2980304 93.2 200.1
22:00:00 10.26 716.49 89.56125 400 599.1 0.9 215.676 0.3010175 82.1 266
23:00:00 6.84 477.66 59.7075 399 421.9 0.9 151.50429 0.3171802 58.5 119.8
585.9

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Chiller#3
Chiller technical details : Let us take an example of 3 nos 800 TR capacity water
colled chillers of centrifuge type. Basically when the chiller is commissioned, data
sheet can be obtained by the manufacturer. This data will be in use and be
beneficial for operation and maintenaces of chillers. Every chiller will have a
unique serial no. Given below is a technical data of 800 TR chiller commissioned
and operational in a large commercial building in Bangalore.
Chiller Model xxxxxxxxx
Starter / VFD .. Starter - Unit Mounted, Wye-Delta
Capacity ……………………………………………..………… 800 Tons
Chiller Input Power …………………………………… 0.562 kW/Ton
Refrigerant Type ……………………………………….. R-134a
(Shipped Separately)
Cooler
Water box Type ................ Nozzle-in-Head, 150 psi
Passes .... ………………………………………………………….. 2
Nozzle Arrangement …………………………………………. D
Tubing .............. Super E2 (SUPE2), .025 in, Copper
TIME
Tons
Efficiency
TR
% OF
COOLING
CAPACITY
V (volts) I (Amps) PF MotorKW IKW
KWH
consumption
9:00:00 767.34 95.9175 95 395 693.8 0.9 246.6459 0.3214297 89.4
10:00:00 377.58 47.1975 58.3 397 421.9 0.9 150.74487 0.3992396 192.7
11:00:00 767.34 95.9175 97.4 399 705 0.9 253.1655 0.3299261 202.8
12:00:00 742.98 92.8725 96.9 392 699.4 0.9 246.74832 0.3321063 413
13:00:00 742.98 92.8725 96.6 389 695.6 0.9 243.52956 0.327774 348
14:00:00 718.62 89.8275 93.2 401 694.8 0.9 250.75332 0.3489373 543
15:00:00 682.08 85.26 83.6 402 609 0.9 220.3362 0.3230357 326.6
16:00:00 633.36 79.17 82.4 399 598.1 0.9 214.77771 0.3391084 516
17:00:00 633.36 79.17 82.1 396 601 0.9 214.1964 0.3381906 290.9
18:00:00 645.54 80.6925 83.6 399 603.6 0.9 216.75276 0.3357697 374.7
19:00:00 669.9 83.7375 88.1 396 594 0.9 211.7016 0.3160197 342.7
20:00:00 669.9 83.7375 86.5 397 622 0.9 222.2406 0.3317519 526.6

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Entering Temperature ………………………………… 55.96F
Leaving Temperature …………………………….... 44.00F
Flow Rate …………………..………………………… 1600.0gpm
Pressure Drop …………………………………………. 25.9ft/wg
Fluid Type ……………………………………………….. Fresh Water
Fouling Factor (hr-sqft-F)/BTU ................. 0.00010
Suction Temperature ………………………………….. 43.21F
Compressor
Map ID ..........………………………………………………….. 21
Flow Fraction …………………………………………… 1.00....
Head Fraction ………………………………………….. 0.97....
Flow Controls
Float Valve Size ……………………………………….. 8 .........
Flasc Orifice ........ ……………………………………………. 29
Control Paramters
Surge/HGBP GVmin ………………………………….. 5% .....
Surge/HGBP Delta Tsmin ..……………………………32.9F
Surge Line Shape Factor …………………………….. -0.04
Surge/HGBP GVmax ……………………………………..100%
Surge/HGBP Delta Tsmax …………………………… 56.37F
Cooler Min DP . …………………………………………. 3.0psi
Condenser Min DP ...……………………………………… 2.2 psi
Weights and Approximate Dimensions
Total Rigging Weight …………………………………… 20684lb
Total Operating Weight …………………………………24847lb
Refrigerant Weight …………………………………….. 1430lb
Length x Width x Height ..... 193.50 x 79.88 x 86.50 in
Condenser
Water box Type ………………………. Nozzle-in-Head, 150 psi
Passes ....... ……………………………………………………….. 2
Nozzle Arrangement ………………………………………… S.
Tubing Spike Fin III (SPK3), …………………………..025 in, Copper
Entering Temperature ………………………………… 85.00F
Leaving Temperature ………………………………….. 95.21F
Flow Rate ……………………………………………….. 2184.0gpm
Pressure Drop …………………………………………... 29.5ft wg
Fluid Type ……………………………………………… Fresh Water
Fouling Factor (hr-sqft-F)/BTU ……………………… 0.00025
Condensing Temperature ……………………………...98.18F
Electrical Data (Starter per Z-415)
Chiller Main Power Voltage/Hertz …………………….. 415-3-50
Oil Pump Voltage/Hertz ……………………………….. 400-3-50
Chiller Input Power ……………………………………… 0.562 kW/Ton
Motor RLA ... ……………………………………….……….. 724
Motor OLTA …………………………………………....... 782...

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Motor LRYA ……………………..……………………...... 1903
Motor LRDA ………………………………………. ......... 5524
Max Fuse/CB Amps ……………………………… ....... 1600
Min Circuit Ampacity …………………………….. ....... 909
Maintenance of chillers:
Condenser approach going up: One of the most common practical applications is that
condenser approach rising. This value can be viewed on the display of chillers. Usually the
approach sensor is calibrated by Manufacturer and recommended by them to verify the data
periodically
Reason: Actually no predefined value for maintaining condenser approach. But most
manufacturers recommend approach to be maintained as less as possible below 2° C even 1° C
a patience value.
 If approach is maintained constant then it is an indication is parameter is maintained
well.
 If approach shoots beyond 4.5°C then maintained constant, then water parameters are
to be checked.
 If continuous variation of approach/fluctuation above 4.5 °C then solution to bring down
is cited below
Chiller surge problem/ tripping:
Possible surge causes are:
1. Poor water flow in condenser.
2. Poor water flow in evaporator.
3. Scaled condenser.
4. Scaled evaporator.
5. Low refrigerant charge.
6. Combination of all above.
7. No condensable gas in refrigerant.
8. Bad refrigerant quality.
Solution – Chiller manufacturer to survey the chillers and check condition and give report on
Condenser maintenance approach and range up to 4-5
Increased approach temperature between liquid refrigerant and leaving water indicates water-
side fouling. With clean tubes, approach temperature will typically vary from 10F at 100% load
to 1F at 10% load. This emphasizes the importance of duplicating the baseline load conditions
when comparing approach temperatures. Ideally condenser approach should be minimal ( < 2
C). Over the period of time as the unit runs, approach degrees raises. For a well maintained
chiller approaches should be <3 at peak load conditions and all times

19
A lower-than-expected approach temperature, accompanied by high condenser head pressure,
high leaving condenser water temperature and higher-than-normal condenser water
temperature differential indicate insufficient condenser water flow rate. A smaller condenser
water temperature differential along with a high approach temperature.
Solution: Check water parameters of condenser. The water parameter to be maintained within
IS 3025 standards.

20
Recommended water quality is given below
But practically depending on water program for cooling tower, it is difficult to maintain all the
parameters as cited above, also the recommendation of manufacture are far below than that
general standard practices IS3025. But to maintain healthy water parameters for purposes of
keeping approach within 4°C, it is recommended atleast to maintain water parameters atleast
10-15% as mentioned before. Still if problem persists Descaling of condenser is mandatory.
Mechanical Descaling of Condensor:
Chiller is to be taken for shutdown. Condenser inlet and outlet valves to be closed. If valves are
not holding properly, dummy plates of condenser pipes to be fixed. Chemicals are used for
Descaling. The most common descaling chemical is ASR-32 chemical. The chemical is mixed with
water in a bucket and pumped into the condenser tubes till the water is emptied. All scale
formation inside the tubes will come and out again next set of chemicals is poured into a tub
mixed with water and recirculates again the end caps are open and brushed with mechanical
brushes will Teflon bristles. The whole set of exercises of chemical circulation is done for 6-8
hours till most of the scales inside the condenser tubes are removed. The hard scales inside the
tubes are thus dissolved and eventually removed off in the process.
Then the condenser valves to be opened and chiller to be switched on by ensure oil pressure is
atleast 130 PSI. When chiller is running at its peak load based on the base demand set by the
operator, the approach to be viewed and recorded. It is mandatory to view and record

21
approach on hourly basis and to ensure healthy maintenance practices is followed to keep up
the approach at a constant desired level.
ASR chemical connection to condenser inlet Scale inside the condenser tube

22
Dummy insertion between condenser inlet and cooling tower Header

23
Checking for scales inside condenser tubes ASR chemicals used for descaling
Jet pump condenser cleaning

24
Tube brushing inside condenser tube
Teflon based brush used for Descaling Chemical recirculation

25
1. Since Oil pressure less than 120 psi when oil is heated to 50 C of chiller # 1 > 4.2, new oil
filter to be replaced and gasket.
2. New expansion float valve for replacement

26
3. Removing the old float valve after chiller shutdown
4. Old float valve removed

27
5. Gasket and new float valve fixing
6. New float valve with gasket ready for fixing

28
7. New float valve fixed and nitrogen purging in progress
8. After vacuuming and achieving vacuum pressure ( 200 micron) the same gas filled back.

29
9. New oil filter fixed for chiller # 2 ( due to low oil pressure fault)
Evaporator Descaling : Similar to the above, if evaporator approach is above 2.5°, then tubes of
evaporator has to be descaled similar in lines of condenser descaling. Evaporator approach >2.5
is a general indication of possibility of scale formation on evaporator tubes.
Chiller energy calculations: Based on all the data, the chiller energy consumption is calculated
and tabulated based on the data below for a real time 800 TR chiller
Chiller Energy
Parameter Units Chiller
Chiller Tonnage Tons 800
Operation Hrs. hrs./day 14
Operation days days/year 365
Load % 96
Design Chiller efficiency Kw/Ton 0.56
Cost KW-hr LC/KW-hr 7.81
Condenser Approach Temp before
cleaning ˚C/º F 7.00
Condenser Approach Temp after
cleaning ˚C/º F 3.00

30
Increase in Condenser Approach
Temp in one year ˚C/º F 4.00 (approach before-after)
1° increased in approach reduce
chiller performance by 3% % 12.00( approach*3)
DESIGN ENERGY CONSUMPTION
@ Design Chiller Efficiency Kw/ton 0.56
*Total Energy Consumption LC/year 17,164,106
CURRENT ENERGY CONSUMPTION
**@ Actual Chiller efficiency Kw/ton 0.627
***Total Energy Consumption LC/year 19,223,798
*Total design energy consumption is a multiplied factor of chiller tonnage, operation hours,
operation days, maximum load and design chiller efficiency and cost of KW/hr.
**Actual chiller efficiency is added factor of design chiller efficiency and multiplied factor of 1°
increase in approach reduce chiller performance by 3% of designed chiller efficiency.
***Total actual energy consumption is percentage of chiller tonnage, operation hours,
operation days, load, design chiller efficiency, cost KW-hr.
This data to be viewed and analyzed periodically to understand the chiller consumption and
efficiency of chillers. The monthly and annual consumption of actual has been mentioned in appendix.
Automatic tube cleaning (ATC) system:
Since descaling ensures a proper chemical is an expensive methodology, most of the areas
where the approaches are on higher side and despite descaling there is no decline of approach
degrees then ATC is recommended. This system utilizes a sponge ball which circulates inside the
condenser tubes. The scaling gets attracted and trapped on the surface of the balls. After this
the ball gets into the collector where it is washed and it is ready for next cleaning. Tube life is
enhanced by preventing fouling.

31
Advantages of using ATC:
 Online cleaning with no chiller downtime
 Fully automatic, effortless cleaning
 Maintains constant optimal performance
 Lowers average condenser temperature by 2°C-3°C
 Delivers 6%-12% operating cost saving

32
A. Water Pumps:
The water system includes primary, secondary and condenser water pumps. The purpose of the
water pump system is
(1) Secondary pumps to transport chilled water from the evaporator to the air-handling units
and primary pump transfers water back from AHU to evaporator of chiller plant
Secondary pumps:

33
2) Condenser pump to transport the condenser water from the cooling tower to the condenser
inside the chiller plant. After the condenser water has been cooled in the cooling tower, it flows
back to the condenser of the centrifugal chillers. The temperature of the condenser water again
rises owing to the absorption of the condensing heat from the refrigerant in the condenser.
After that, the condenser water is pumped to the cooling towers by the condenser water
pumps.
Condenser pump:

34
3) Primary Pumps: The chilled water is cooled in three centrifugal chillers and then is
distributed to the cooling coils of various air-handling units located on individual floors. The
temperature of the chilled water leaving the coil increases after absorbing heat from the
airstream flowing over the coil. Chilled water is then returned to the centrifugal chillers for re-
cooling through the chilled water pumps.
Primary pumps:

35
Below mentioned is the pump specifications which has to be understood to check and maintain
healthiness of pumps. In usual practices stand by pumps are available in case if any one of the
pump fails. Generally load on pump terminals are checked and verified with the rated load.
Speed can be checked with devices like ultrasonic Tachymeter, to understand the speed in
which its running. Couplings are checked for damages, misalignment etc. Electrical motors are
to be checked for winding etc.
HVAC Water pump specifications

37
COOLING TOWER
The cooling tower is used to cool the water that absorbs heat from the compressor and the
condenser. When water flows through these components some water gets evaporated, to
make up this loss some water is also added in the cooling tower. The cooling tower is of
evaporative type. Here the water is cooled by the atmospheric air and is re-circulated through
the compressor and the condenser.
Cooling towers are the primary component used to exhaust heat in open recirculating cooling
systems. They are designed to maximize air and water contact to provide as much evaporation
as possible. This is accomplished by maximizing the surface area of the water as it flows over
and down through the tower structure. First, the water is distributed evenly across the top of

38
the cooling tower structure. Tower distributions decks can be a series of spray nozzles oriented
up or down (like a landscaping sprinkler system) to uniformly distribute the water over the
tower structure.
In some cases, the distribution deck may just be a series of holes through which the water falls
onto the tower structure. Regardless the distribution deck must uniformly apportion the
recirculating water across the tower structure. Broken nozzles or plugged orifices will impede
uniform distribution across the tower structure, negatively impacting the overall heat exchange
capacity of the system. As the water falls from the distribution deck, the surface area is further
expanded in the fill section. Older tower systems may feature splash bars made of plastic,
fiberglass, or wood that serve to break the falling water into tiny droplets. In recent years,
many different forms of labyrinth like packing or film fill have been incorporated. The closely
packed nature of film fill causes the water to travel through this portion of the tower in thin
streams, improving thermal efficiency and the evaporation rate, thereby increasing heat
rejection. To minimize losses due to drift and help direct airflow into the tower, louvers and
drift eliminators are commonly used. Louvers are most often seen along the sides of the tower
structure, while drift eliminators reside in the top section of the tower to capture entrained
water droplets that may otherwise leave through the stack.
Damaged or incorrectly oriented louvers along with damaged drift eliminators will lead to
excessive losses due to drift from the tower structure. Therefore, louvers and drift eliminator
sections should be routinely inspected and repaired to ensure optimal water usage. After the
water passes through the fill it cascades down to a collection basin at the base of the tower
structure. From the basin the cold water can be pumped back into the system to extract
process or comfort cooling needs and begin the cycle all over again. By design, cooling towers
consume large volumes of water through the evaporation process to maintain comfort cooling
or process cooling needs, although they use significantly less water than similar capacity once-
through cooling systems. Because the evaporative loss is water containing little to no dissolved
solids, the water remaining in the cooling tower becomes concentrated with dissolved solids,
which can lead to scaling and corrosive conditions. To combat these problems, water with high
total dissolved solid content must be drained from the system via “blow down.” The associated
losses caused by blow down, evaporation, drift, and system leaks must be accounted for by
system make-up requirements.

39
Cooling tower hood
Inlet from
condenser
Outlet to
condenser

40
Let us take an example of cooling tower of 800 TR of 3 no’s, equal to that of chillers as mentioned in the
previous chapter. The technical data sheet has to be obtained from the manufacturer of Cooling towers
and to be recorded and used by the maintenance personnel to calculate data and carry out
maintenance activities. An actual technical data sheet of an operational cooling tower is mentioned
below
TECHNICAL DATA SHEET OF COOLING TOWER
Designed Duty Conditions:
Hot Water Temperature : 95.00°F
Cold Water Temperature : 85.00°F
Wet Bulb Temperature : 78.00°F
Water Flow Rate : 2400.00 USGPM
Heat Rejection Capacity : 30,26,700 KCal/hr ( 12.04 x 106 BTU/hr)
1. Components classification no. : ID-2480F4C2
(With FRP Cowl for reducing the noise)
2. Type : Induced Draught Counter flow
3. Distribution : Gravity flow (static)/ Main header and
branch arm system
4. Wet bulb approach : 7°F
5. Dimensions (mm) # Approx. : 7200 x 6000 x (3715 + 1500)
6. Operating wt. (kg) : 11200
7. Fill wetted area (sq.) : 6605
8. Evaporation loss : 1.00%
9. Drift loss : 0.05%
10. Total water loss : 1.05% (without bleed off)
11. Fan dia. (mm) : 1800
12. No. of fans : 4 (Two per cell)
13. Air flow (CFM) : 50,700 CFM per cell x 4
14. Tip velocity (m/min) : 3925
15. Fan material & Type : Cast Aluminum, Axial flow
16. Motor HP : 10 HPx 04 Nos. (Two per cell)
RPM : 710
Type : Squirrel Cage (IP55), TEFC
17. Make : New India (NEI)
18. Tower structure and Basin : FIBREGLASS
19. Fills : High efficiency PVC 'Fills pack with
UV stabilization

41
20. Drift Eliminators : PVC
21. Fill support : HOT DIPPED GALVANIZED
FRAME
22. Bird screen : HOT DIPPED GALVANIZED
FRAME
23. Distribution supports : HOT DIPPED GALVANIZED
FRAME
24. Ladder : M.S.H.D.G.
25. Hardware : Electroplated
Maintenance of cooling tower:
Cooling tower capacity & efficiency
Rated Capacity of cooling tower is in same capacity of chiller, 800 TR . The data sheet from
manufacturer and found the same to be in order It is observed that cooling towers are placed in
a well installation, two sides there is blockage of air flow due to the Walls and only one side air
entry was seen prominently.
Position of cooling tower: Location of cooling tower matter a lot and this has to be taken care
initially during the design/commissioning itself. Basically the following to be taken care in the
nascent stage it to prevent further problems.
 It should be positioned so that it is free on all 4 sides ( atleast 4 entries)
 It should be located at such a place so that no construction activity is going on the
vicinity. No dust accumulates or possibility of it to entering into cooling tower anywhere
in the surrounding.
 It should be noted that no foreign particles can enter the body during any strong winds
etc.
 The fan can extract air and there is no obstruction of heat rejection or nothing above
fan.
 No hot air/extract fans/exhaust fans given hot air near the vicinity of cooling tower else
hot air will disturb the heat exchangers of water inside cooling tower ( CDW Δt).
If Cooling tower is surrounded by walls on 3 sides there is chance of Bypass of hot air with air
intake
Sizing of the cooling tower: Generally it is mandatory that the cooling tower tonnage is atleast
1.25 times higher than the chiller tonnage in order to get a good condenser inlet temperature,
and maintaining good condenser pressure.

42
Whether with the present load status we can run one sequence chiller cooling tower condenser
pump.
With all notified observations one chiller –Cooling tower and one condenser pumps will fall
inadequate due to below possible reasons:
• As notified cooling tower might not be working to fullest potential
• As notified there might be chances of condenser scaling inside chiller
• As notified flow rates might not be adequate as per improper condenser water
balancing
• Across the De-coupler line if a flow meter is fixed we can observe the quantum of
bypass
• Currently the Secondary pumps are running in Manual mode and @ fixed HZ.
• Entire Pumping system has to be made automatic and set in Auto mode.
• All Tenant ( retailers, office cabins etc) Chilled water valves to be cross checked for
Functionality as the backpressure should modulate
VFD of the pump with DP sensor sensing the same and for potential benefits of Energy
savings
Condenser pressure: condenser pressure plays an important role in knowing the flow of
refrigerant and water inside the condenser tubes, Usually in this 800TR machine, the approach
condenser pressure is to be maintained within 750-850 KPA. If the condenser pressure is higher
than 850KPA, there is a trouble indicating variation in Δt of condenser, higher cold water inlet
temperature not performing its action of reducing water temperature to a set value. If the
pressure rises up to 900KPA, the chiller automatically trips.

43
Water balancing reports:
The above mentioned water balancing report has been studied during the commissioning stage
of the equipment’s. The balancing has been done by rotating the balancing valves at a
particular pressure and locked at that stage for the flow and pressure to be constant at all
points of time. Based on the above chart timely pressure can be checked using ultra sonic
digital flow meter to analyze the flow. The flow can be taken to calculate the tonnage of chiller
at any point of time, also the IKW factor of chiller.
Condenser temperature (Δt): Condenser temperature difference is also an important factor of
indicating the performance of the cooling tower. In usual practice the condenser Δt to be
maintained less ≤ 4~5°C. The cold water inlet to be around 25°C (at humid cities like Bangalore)
and cold water outlet to be not more than 30°C. If cold water inlet raises above 25°C and
crosses 30°C then the chiller trips. This is a direct indication that cooling tower performance is
decreased due to insufficient airflow and heat exchange between air and water. Cooling tower
to be free on all sides so that the fan can extract maximum air from surroundings the thumb
rule says all 4 meters to be free with no obstruction up to 4 from cooling tower body.
Control Ref Location
Valve
Size
(mm)
Design
Flow
(GPM)
Design
Pressure
Drop at F/O
(bar)
Initial
measure
d drop at
F/O (bar)
Pressure
drop (bar) Flow (GPM)
% of
Design
Turns
Kv
Value
Chiller No 01 Plant Room 250 1600 0.02 0.14 0.36 1812 113 10.0 1015
Chiller No 02 Plant room 250 1600 0.02 0.14 0.1 1676 104.7 12.0 1211
Chiller No 03 Plant room 250 1600 0.02 0.14 0.09 1624 101.5 12.0 1211
Chiller No 01 Plant Room 300 2400 - 2519.6 - 2410 100.4 9.0 -
Chiller No 02 Plant room 300 2400 - 2186.3 - 1676 104.7 14.0 -
Chiller No 03 Plant room 300 2400 - 2608.6 - 1624 101.5 9.0 -
Cooling Tower - 01 Terrace 300 2400 - 1857.8 - 2385.3 99.4 14.0 -
Cooling Tower - 02 Terrace 300 2400 - 2738.2 - 2512 104.6 12.0 -
Cooling Tower - 03 Terrace 300 2400 - 2663.8 - 2420 100.8 11.0 -
Shaft 01, 01A & 02 Basement 250 1837 0.06 2328.4 0.29 1810 98 8 762
Shaft 01B Basement 150 630 0.03 764.56 0.43 633.78 100.6 8 219.8
Shaft 03 Basement 150 362 0.11 341.33 0.19 423.64 117 8 219.8
Shaft 04 Basement 200 1016 0.16 866.4 0.47 1013.5 99.7 6 335.1
Shaft 05 Basement 200 825 0.16 753.46 0.3 822 99.6 8 335.1
REMARKS : Water Balancing is done with 4 Nos Secondary pumps running @ 45 Hz
WATER FLOW READING- CONDENSOR
WATER BALANCING REPORT
WATER FLOW READINGS - CHILLER
Settings
FINAL READINGS
WATER FLOW READING- COOLING TOWER

44
Chemical Dozing in cooling tower:
This is the most important aspect in any water cooled system, which employs cooling tower.
Adequate quantity of chemicals are dozed in cooling tower basin of chemicals dozed in cooling
tower basin to keep check on growth of bacteria/algae to control hardness TDS in turn which
prevents scale formation to prevent growth of microorganisms in cooling tower body to
maintain PH ( keep system in alkaline mode $ diminish acid contents) to prevent fouling.
In any application the following chemicals are used
 Biocides  anti algae
 Bio nil  Corrosion
 PH corrector
 Anti scalant  reduce hardness
These chemicals are manually put into the dozing system.
Whether maintaining the water hardness less than 200 ppm and TDS less than 1500 ppm as
per chiller standards after using the chemicals (anti scalant, Biocides).
Cooling tower Dosing needs to be fully atomized system.
Mechanically maintaining cooling tower: Condenser water and makeup water parameters to
be checked and monitored on daily basis. If abnormalities found then:
 Recheck the chemical program of cooling tower
 Add shock absorbing chemical if required
 Manually shut down the cooling tower and remove the algae formation. Note before
algae form there will be slime formation, which is an indicator of further algae growth
inside cooling tower.
 Check FRC level in cooling tower. If chlorine level is nil then it is an ideal habitat for
microorganisms to grow.

45
Cooling tower inlet and outlet sensors connected to BMS: It is ideal to connect the cooling
tower parameters to integrated building management systems. It helps the maintenance
personnel to check the ongoing parameters at all times. The values help in identifying the
problems and help to diagnose the variances.
Condenser
water outlet
sensor

46
COOLING TOWER SYSTEM CALCULATIONS:
To properly operate and maintain a cooling tower, there needs to be a basic understanding of
the system water’s use. Water use of the cooling tower is the relationship between make-up,
evaporation, and blow down rates. There are a couple simple mathematical relationships
between the blow down rate, evaporation rate, make-up rate, and cycles of concentration of a
cooling tower that are very useful to understand the principal flow rates. The first relationship
illustrates the overall mass balance consideration around a given cooling tower:
1. Evaporation rate =
( )
Δt is degree centigrade which is the difference in cooling tower inlet and outlet temperatures
2. low down =
3. Cycles of Concentration =
4. Make-up =
Let us consider below a cooling Tower, 3 nos of 800 TR capacity as per data sheet catering a
large commercial building from the time it starts operation till it is closed.
Condenser
water inlet
sensor

47
COOLING TOWER CALCULATIONS:
The values are tabulated based on calculations using formulae above.
consumptioninKL consumptioninKL consumptioninKL
Hrs Timings CoolingTower#1 CoolingTower#2 CoolingTower#3 Blow Down(Bleed)KL Cumulative
8:30A.M
1hr 9:30A.M 3.1 3.1
10:00A.M
2hr 10:30A.M 6.2 6.2
11:00A.M
3hr 11:30A.M 9.3 9.3
12:00P.M 3.1
4hr 12:30P.M 12.4 12.4
1:00P.M 6.2
5hr 1:30P.M 15.5 15.5
2:00P.M 9.3
6hr 2:30P.M 18.6 18.6
3:00P.M 12.4
7hr 3:30P.M 21.7 21.7
4:00P.M 15.5
8hr 4:30P.M 24.8 24.8
5:00P.M 18.6 9.75
9hr 5:30P.M 27.9 27.9
6:00P.M 21.7
10hr 6:30P.M 31 31
7:00P.M 24.8
11hr 7:30P.M 34.1 34.1
8:00P.M 27.9
12hr 8:30P.M 37.2 37.2
9:00P.M 31
13hr 9:30P.M 40.3 40.3 32.55 32.55
10:00P.M
14hr 10:30P.M 43.4 43.4
14.5hr 11:00P.M 44.95 44.95 132.2
3.25
3.25
3.25

48
Total Time 14.5 hrs
a) Evaporation Rate =
Flow rate = 2500 GPM
considered from Flow meter
reading of M/s Carier
(1.8 x 5 x 2500)/1000
22.5
b) Blow Down (m3/hr) (Evaporation rate/COC)-1 COC=3 COC (Cycle of Concentration)
6.5 KL per hour
Actual blow down per day 30 min
c)
Total water required /lost for blow down per
day
3.25
KL (or m3)
d) Make up for Cooling Tower/day 45 m3 For 14.5 hrs
e)
Total water required for 1 cooling tower for 1
day
48.25 c) + d)
When 2 cooling Towers running
a) Total time 14.5 hrs 8:30 A.M to 11:00 P.M
b) Make up for 2 Cooling Tower 90 KL (or m3)
c)
Total water required /lost for blow down per
day
3.25 KL (or m3)
d) Total water required for 2 cooling Towers 93.25 KL (or m3)
3rd Cooling Tower
a) Total Time 10.5 Hrs 11:00 A.M to 9:30 P.M
b) Evaporation Rate 22.5
c) Actual Blow down/day 30 min
d) Total water required/Lost in blow down 3.25 KL ( or m3)
e) Make up for 3rd cooling tower 32.59 KL ( or m3)
f) Total water required only for 3rd cooling tower 35.84 KL ( or m3)
Grand Total water required per day when all
cooling towers are running
129.09 KL ( or m3)
The Make up water source is
the Raw water filtered through
WTP. ( RO water not
considered here).
When 1 Cooling Tower Running
8:30 A.M to 11:00 P.M
(1.8 X Delta T X Flow Rate of condensor)/1000
Cooling Tower Water Requirements

49
Blending ratios for water based on number of chillers in operation: In most of modern commercial
buildings and cities where pure water is scarce, water from other sources like recycled water from STP
with further treatment like reverse Osmosis/ultrafiltration is used. If recycled water is used for cooling
tower make up’s then it is suggested to analyze the parameters as per water recommendation.
Especially recycled water coming through RO will be more acidic, which is harmful to metal pipes and
tubes. Further if TDS is below the recommended bandwidth then the water becomes incapable of heat
exchanging. It is recommended to blend the recycled water with normal water on particular blending
ratios as mentioned below. Basically these blending ratios if used will prevent corrosion of pipes and
tubes and helps in longevity at the pipes. Water to be mixed depending on number of machines in
operation is given below.

51
Quarterly a year cooling tower is to be taken for a shut down and following to be done
 Remove all fills and physically observe for damage fills, deposit fills etc. Fills are to be
changed once every two years.
 After fills are removed water to be let in to check for functionality of all spray nozzles, if
spray nozzles found to be chocked then it requires immediate replacement.
 Check for drift eliminations if drift eliminate.
 If drift eliminations are faulty, it may effect heat dissipation
 Check at condenser basin for any rust formation. If rust forms at basin then there is a
possibility of it enters the condenser tubes and thereby gradually leading to
deterioration of heat exchange capability.
 Check for PVC header pipes of cooling tower. If pipe is blocked due to large deposits of
scales foreign particles then end caps to be removed and thoroughly brushed and
cleaned. This is again indicator of scaling, foreign particles entry into cooling tower.
The condition of fills across cooling towers
• It was observed the nozzles and spray is non-uniform and fins are damaged in the
cooling tower.
• Cooling tower requires fin requirement and servicing to maintain the same properly
• Cooling tower manufacturer can be called for Inspection and repairs and mend the same
For proper functionality.
• AMC to be given for proper maintenance of cooling towers.
Shown below is a real time solution of changing fills of cooling tower and clearing all the blocks
of distribution pipes.

52
1. Fills arrived and stored
2. Cooling tower Basin cleaning ( Manual)

53
3. Existing fills removed from cooling tower and checking the nozzles/splash cups
4. Removing the blockages from distribution pipes and checking all splash cups

54
5. Pipe block removal of cooling tower headers
6. Sample and condition of old fills removed from cooling tower

55
7. Algae content mass removed from cooling Tower
8. Manual cleaning and removal of all masses

56
9. Cleaned cooling tower basin after water wash
10. FRP coating with primer

57
11. FRP Coating on cooling tower Basin.
PROPERTIES OF WATER
Water and its properties plays a very important role in the HVAC system. In fact it is the water
which is used as medium for heat exchange inside condenser and heat exchange inside
evaporator of chiller. Again water is transported into AHU from evaporator is used as a heat
exchange medium with air, which makes air to be cooled and provided to area to be cooled.
CHILLER
Condenser
Evaporator
AHU
Water Water
Water
Outlet
Water
inlet

58
Now this water which is essential in chiller as well as AHU should fulfill certain criteria in order
to perform well in terms of heat exchange at the same time ensure it doesn’t have effect the
tubes inside the chillers and AHU through which it traverses. The performance of water
depends on the chemistry of water. The following parameters to be looked into
1) Hardness
2) TDS
3) Alkalinity
4) Chlorides
5) Silica
6) PH
7) Turbidity
PH:
PH should be neutral. Neutral PH means it should be equal to or near the value 7.
If PH<7, then it is acidic
If ph>7, then it is basic
It is always best to have PH 7 or even slightly greater but not less. Low PH indicates acidic and
severely puncture the metals especially the copper tubes through which it traverses. It is better
recommended for a maintenance practitioner to keep the PH value slightly basic up to 8.5 and
operate the plant. Still higher values of PH may lead to gradual corrosion. PH can be boosted by
adding PH booster like caustic soda in a correct proportion so that it is maintained below 8.5 at
all times.
Turbidity:
It is the measure of suspended particles in water. Suspended particles can be in the
form of smoke, dust and other foreign particles which may not be visible to the naked eye.
Usually turbidity is higher in places wherever there are constructive mining activities going on
nearby. Turbidity is measured in terms of NTU. Ideally turbidity should be within 5NTU as per
IS3025 standards.
TDS:
TDS refer to the presence of compounds present in water, which contains carbon. The
compounds can be solid compound, chemical compound or gaseous compound. Generally TDS
is the presence of suspended minerals dissolved ions of suspended metals. These compounds
are suspended in water and can’t pass through a filtration process. Generally it differs from TSS
(total suspended solids) in which the suspended solids cannot pass through ≤2 micron filters. As
per IS 3025 standards the TDS should be less than 500mg/liter. For HVAC applications TDS
recommended in cooling tower makeup should be about 250PPM depending on program at
condenser basin it can be up to 1500PPM.

59
Practically TDS can be totally removed from water but it can be separated by using
reverse osmosis process. A typical reverse osmosis plant consists of a membrane made of poly
amide in a spiral wound form. The water is allowed to pass through this membrane at a very
high pressure. The permeate that comes out of the membrane will have a very less TDS. The
solvent which isn’t allowed to pass consists of very high TDS, which is drained out through a
reject pipe. TDS shouldn’t be too less also in water for HVAC application for the sole reason that
it has to perform its basic function. Practically very less TDS water may not do the function of
heat exchange with refrigerant inside the condenser.
Hardness:
Hardness of water is due to the presence of calcium and magnesium ions in water.
Higher quantities of calcium and magnesium makes the water very hard or also called hard
water. Hard water may cause corrosion when it traverses through metal tubes. Hence hardness
of water should be minimum. Total harness of water is the sum of total calcium and total
magnesium ions in water. Generally hardness of water used for cooling tower makeup can be
up to 50 depending on optimum COC at condenser basin it can be up to 200PPM. Water
hardness can be controlled by using a softener plant. Softener plant consists of vessel with
resins packed inside it. The resins are golden colored spherical forms and have sites on its
surface which is sodium ion rich. The hard water having ions like ca2+
, mg2+
when flowing in
opposite direction happened into this na+
ion of gradually the ca+
and mg2+
gets reduced and
thereby hardness of water also gets reduced. Once na+
ions are replaced with ca2+
and mg2+
ions they are regenerated by using water contains salt solution (NACL). Then the resins are
changed within fresh sodium ion and ready to take on harness of water.
Silica:
Silica is the compound of silicon and oxygen. Silica content in water can form scale
deposits on metals where water comes in contract. It is advisable to crack and ensures silica or
Sio2 is less than 50PPM at condenser basin.
Chloride:
Chloride ions constitute total mineral content in water. It is collateral increase salinity in
water. In makeup it is optimum to have less than 50PPM and in the condenser depending on
COC program it should be less than 200PPM. If the above parameter especially PH hardness and
TDS are not controlled properly it is evident that metals corrode form scales, cause bio fouling
on the system which would decrease the system performance and efficiency. It would be time
consuming and expensive to charge the metal pipes remove scales etc. Hence it is necessary to
protect the process equipment’s against above variances of water parameters.
An ideal cooling tower condenser water dosing system should consist features to overcome
1. To remove coarse debris and larger life forms.

60
2. To remove fine suspended matter to prevent erosion and to prevent the formation of
accumulations of material which would adversely affect heat transfer and possibly induce
corrosion Also, large accumulation of settled out solids can choke cooling system including
cooling tower ponds
3. To remove excess free carbon dioxide (CO2) and iron/manganese present in water
particularly in case of ground water More CO2 than equilibrium is aggressive, while less from
equilibrium can give rise to calcium carbonate (CaCO3) scale formation. Similarly, large 1
amount of iron and manganese can foul the tubes and induce corrosion.
4. To inhibit the growth of micro-organisms on heat exchange surfaces
5. To prevent the formation of scale this would affect heat transfer and impede flow of water.
Though calcium bicarbonate is by far the most common scale found in cooling water system,
attention should also be paid on less commonly found scale like calcium sulphate, calcium
phosphate, magnesium silicate, etc.
6. To remove the corrosive potential of the cooling water due to dissolved oxygen, dissolved or
suspended salts, alkaline or acidic water velocity, temperature, microbial growth, etc.
Let us now have an insight of water parameters used in the cooling tower application above for
last 9 months. In this application tanker water (water from bore wells) is used.
1. Condenser water

61
s.no month TDS Hardness Chloride silica
1 14-Dec 3560 1075 130 90
2 15-Jan 3280 1000 130 70
3 15-Feb 2950 950 130 70
4 15-Mar 2710 800 130 70
5 15-May 3520 1150 130 70
6 15-Jun 2450 725 130 50
7 15-Jul 3200 825 130 70
8 15-Aug 4050 1050 130 80
9 15-Sep 2610 575 130 70
10 15-Oct 2490 550 130 60
Condenser water
0
500
1000
1500
2000
2500
3000
3500
4000
4500
14-Dec
15-Jan
15-Feb
15-Mar
15-May
15-Jun
15-Jul
15-Aug
15-Sep
15-Oct
1 2 3 4 5 6 7 8 9 10
TDS
Hardness
Standard
condenser
TDS
Standard
condenser
hardness

62
2. Makeup water
0
20
40
60
80
100
120
140
160
180
200
14-Dec 15-Jan 15-Feb 15-Mar15-May 15-Jun 15-Jul 15-Aug 15-Sep 15-Oct
1 2 3 4 5 6 7 8 9 10
Chloride
silica
Standard
condenser
chloride
Standard
condenser
silica
s.no month TDS Hardness Chlorine Silica
1 14-Dec 780 250 40 10
2 15-Jan 780 250 40 10
3 15-Feb 780 250 40 10
4 15-Mar 800 250 40 10
5 15-May 760 250 40 10
6 15-Jun 820 275 40 10
7 15-Jul 800 270 40 10
8 15-Aug 810 270 40 10
9 15-Sep 810 200 40 10
10 15-Oct 800 200 40 10

63
0
100
200
300
400
500
600
700
800
900
14-Dec 15-Jan 15-Feb 15-Mar 15-May 15-Jun 15-Jul 15-Aug 15-Sep 15-Oct
1 2 3 4 5 6 7 8 9 10
TDS
Hardness
Standard TDS
makeup
Standard
hardness
makeup
0
5
10
15
20
25
30
35
40
45
50
14-Dec 15-Jan 15-Feb 15-Mar 15-May 15-Jun 15-Jul 15-Aug 15-Sep 15-Oct
1 2 3 4 5 6 7 8 9 10
Chlorine
Silica
Standard
chloride
makeup
Standard
silica
makeup

64
COC Limiting factors:
Higher cycle of concentration is advantageous form saving of water as in the water passes form
cooling tower through header pipes to the condenser of the chiller and returns till it is lost in
blow down. This is considered as a cycle of water journey. On the other hand keeping large COC
tend to increase the ca+
and mg+
ions in the water leading to hardness thereby lead to scaling.
Hence it is advisable to keep the COC optimum following in the concerns arising out of
variances of water.
Corrosion:-Water when contact with metal surface converts metal into its oxide. The metal
then starts slowly dissolving; this is mainly due to high mineral deposition in water and
presence of oxygen.
Scaling:- As mentioned earlier calcium and magnesium ions in water constitute into hardness.
They are usually soluble in water with higher concentration they tend to lose their solubility
called inverse solubility. They precipitate out and tend to deposit on the metal surface. These
Makeup water for
cooling tower

65
deposits are called “scale” the scale formation limits heat exchange capability of the system. It
lets uncontrolled they lead to puncture/failure of metal due to impending thermal stress.
Fouling:- water contains suspended foreign particles of all kind. The suspended foreign particles
are usually process oils, fine dust particles or flying particles. Fouling occurs due to poor water
flow low pressure, exposure of cooling tower to contract areas, mining etc. these particles
come out of the solution and form deposits like scale. Similar to scales they affect heat
exchangers capabilities and reduce thermal surface area thereby reducing overall efficiency of
cooling tower. Fouling usually happens when NTU>5, large NTU’s are indication of higher
fouling.
Biofilms/Algae content: - Water also contains microorganism’s species of different kind. These
microorganisms/algae secrete matter called slim. These are sticky in nature and sticks to the
fills etc thereby blocking free water flow and reducing water pressure. They indirectly lead to
corrosion through the process of metabolism leading to uncontrolled corrosion.
Treatment Options
Traditional water treatment programs are designed and implemented to account for the
system concerns outlined above. This ensures the tower system operates optimally and
achieves the needed cooling requirement. These programs consist of chemical additives
including corrosion inhibitors, dispersants, scale inhibitors, and biocides that function to protect
the cooling system and keep heat exchange surfaces clean and free of deposits or bio-films.
When this is accomplished, maximum cycles of concentration can be achieved, and the cooling
system can be operated at peak efficiency both in terms of water use and energy use. Beyond
traditional water treatment programs there are options to build upon the current program,
improve the current program, or replace the current program.

66
Auto Dozing system skid
Auto dozing system in cooling tower is recommended if despite recharging chemical program
and using proper chemicals the parameters are shooting up. If nothing can be done on design
of cooling tower, if it can’t be re-posited, if water can’t be retreated then it is best to install an
auto dozing system with a program where chemicals are dozed automatically as varied
parameters the values are permanently recorded through probes and controller via a control
panel. As and when parameter vary beyond the set/desired value then the probe/sensor signals
the dozing pumps to doze the required quantity into cooling tower and dozing continues till the
parameters are well within the set values
Side stream filter: If fouling in cooling tower is very high then side stream filter is
recommended sometimes. It is possible to control scale formation but fouling will be high due
to entry of foreign particles. Ideally in water sample of cooling tower the turbidity should be
maintained less than 5 NTU. If it’s more and as mentioned earlier position of cooling tower
can’t be changed from side stream filter to be installed which prevent the fouling/foreign
particles entering into the condenser.
Dozing
Tank
Dozing
Pump
Electrical
panel

67
The sample showing increase in turbidity of CT water and as per lab analysis report is shown
below.
Summary of observation for improving the system
Additional cooling tower might be required to enhance the condenser water flow rate and
keep a good approach temperature in case the problem does not solve after the below
mentioned remedies as its observed the cooling tower isn’t well installed and hence deration
might be one of the reasons apart from below observations
1. Chiller condenser descaling.

68
2. Secondary pump in Auto mode commissioning.
3. Balancing of chilled and condenser water flow rates for entire plant and low side works.
4. Checking/ Rectifying / Making chilled water two way valves functional for Tenant areas.
5. Implementation of Automation system of chemical dosing to ensure scientific dosing else
chemicals would get wasted and not useful.
6. Cooling tower maintenance contracts.
7. All Pump flow checks- using flow meters.
8. Overall operation of plant and logs to be maintained by professional agency with AMC for all
critical systems Chillers , pumps , cooling towers , water balancing etc.

69
CHAPTER 4
AIR HANDLING UNIT ROOMS

70
AIR HANDLING UNIT ROOMS
The air handling units are very important parts of the central air conditioning plants, packaged
air conditioning plants and also the roof mounted split air conditioning systems. As the name
suggests air handling unit is the box type of unit that handles the room air. It comprises of the
cooling coil over which the hot return air from the room flows, gets cooled and flows back to
the room to cool it. The circulation of the air is carried out by the blower. The filter in the air
handling unit enables cleaning of the air. The air handling units are also called as fan coil units in
case of roof mounted split AC units, since they comprise of the fan and the cooling coil. The air
handling units are installed at the different places in the building to be air conditioned. They are
connected to the cool air supply and return air ducts which are laid in all the rooms to be
cooled. In case of the central air conditioning plants the air handling units are installed on the
floor, while in case of the split air conditioners, they are mounted on the roof inside the room
above the false ceiling. In case of packaged units they can be installed on the floor or the roof.
The air handling units are installed in the various parts of the building that are to be air
conditioned, in the place called air handling unit rooms. The air handling units comprise of the
cooling coil, air filter, the blower and the supply and return air ducts. The chilled water flows
through the cooling coil. The blower absorbs the return hot air from the air conditioned space
and blows it over the cooling coil thus cooling the air. This cooled air passes over the air filter
and is passed by the supply air ducts into the space which is to be air conditioned. The air
handling unit and the ducts passing through it are insulated to reduce the loss of the cooling
effect.

71
AHU filters
Chilled water inlet and outlet
Filters
Inlet
water
Outlet
water

72
Blower and pulley:
Sweating:
Pulley
Sweating
Blower
Motor

73
Maintenance of AHU’s:
AHU’s are an integral part of HVAC towards the low side. It is the main area which caters
cooling tower and humidity control at the area where it is intended. If cooling is desired
temperature in the area is not achieved then first aspect any engineer/technician looks into the
AHU whereas the name indicates Air Handling unit that takes place. In most of the common
area the problem associated with AHU of the blower design inadequate or the blower motion
rotary in opposite direction. The design of the blower has to be taken care of in the design
stage itself depending on the CFM/ air flow the air handle is intended to give. In usual practice
as far as maintenance are concerned the following is looked into checking the terminal of blow
motor blower technically the amps of 3ø that is RYB to be checked using a clamp meter.
There will be a design rating on the terminal for example if design rating is 10A then
R=8.5A
Y=9A
B=9A
If the results are greater than 6A on each phase then the terminals are healthy and it is
understood that they are taking equal load. But if found less than 6A then pulley of blower and
motor to be checked and replaced, lesser the pulley diameter more the rotation given by
formula
The rotation of blower and motor can be checked using a tachometer which shows the speed
(N) in the unit of revolution per minute. The motor and blower are connected by means of a
transmission belt. These belts are usually made of rubber material and available in various
sizes. It is mandatory to inspect the tension of belts and periodically change it if much wear and
tear is to be found.

74
a. Filters: Filters are an important part of AHU. The filters prevent the solid, dust and
other suspended particles entry into the unit and thereby ensuring good quality of air
coming to common area. Commonly filters are available in various sizes. The filter capacity is
mentioned in microns (10^-6). Less the microns more is its filtering capacity. In simple words,
even the minute particles aren’t allowed to pass through. Below mentioned is the list of AHU
filters with their dimension and quantity floor wise at a retail area.
S.no Floor AHU
Number
Width Height Diameter Quantity
1 LG AHU1 475 630 48 8
2 LG AHU2 565 760 48 8
3 LG AHU3 562 760 48 8
4 LG AHU4 475 765 48 8
5 LG AHU5 610 610 48 8
6 LG AHU5 610 305 48 4
7 UG AHU1 510 630 48 6
8 UG AHU2 760 610 48 9
9 UG AHU3 760 630 48 4
10 UG AHU4 760 560 48 9
11 UG AHU5 560 760 48 4
12 UG AHU6 560 760 48 8
13 FF AHU1 760 630 48 4
Filters

75
14 FF AHU2 760 610 48 9
15 FF AHU3 760 630 48 4
16 FF AHU4 575 510 48 12
17 FF AHU5 760 560 48 4
18 FF AHU6 640 640 48 6
19 FF AHU7 610 610 48 4
20 FF AHU7 305 610 48 2
21 SF AHU1 760 630 48 4
22 SF AHU2 760 610 48 9
23 SF AHU3 760 630 48 4
24 SF AHU4 760 500 48 9
25 SF AHU5 760 560 48 4
26 SF AHU6 760 630 48 4
27 SF AHU7 610 610 48 4
28 SF AHU7 305 610 48 2
LG - Lower Ground
floor
UG - Upper Ground
floor
FF - First floor
SF - Second floor

76
AHU test with BMS:
Below mentioned is the tabulated record of chilled water inlet and outlet temperatures at AHU.
It is to be note that wherever the chilled water inlet and outlet temperature differences are <4°
C, then the indication is that enough heat exchange not happening at coils. Physically good
sweating is an indicator that good heat exchange is happening. The temperature difference and
inlet and outlet of AHU’s to be equal to 4°C. Beyond 6°C, then it is again indicator that coils are
blocked and requires cleaning.
Floo
r
AHU
no inlet outlet
delta
temp
filter
status
supply
Dampe
r status
return
Damper
status Sweating Status Remarks
LG AHU1 9.8 14.6 4.8 normal normal normal normal none
LG AHU2 10.1 14.3 4.2 normal normal normal normal none
LG AHU3 9.2 11.2 2 normal normal normal Less sweating
coil is bloked & belt is loose, Dscaling
to be done
LG AHU4 10.2 16.4 6.2 normal normal normal Less sweating AHU Dscaling to be done
LG AHU5 10.8 13.5 2.7 normal normal normal Less sweating AHU Dscaling to be done
UG AHU1 7.9 12.6 4.7 Normalnormal normal normal none
UG AHU2 8.1 15.3 7.2 Normalnormal normal Less/No sweting AHU Dscaling to be done
UG AHU5 8.3 12.3 4 Normalnormal
one not
connect
ed to normal none
UG AHU6 9.6 12.4 2.8 Normalnormal normal Less/No sweating AHU Dscaling to be done
FF AHU1 8.4 12.1 3.7 normal normal normal Less/No sweating AHU Dscaling to be done
FF AHU2 8.2 11.2 3 normal
one not
connec
ted to normal Less/No sweating AHU Dscaling to be done
FF AHU3 8.4 13.3 4.9 normal normal normal Normal none
FF AHU4 8.7 14.1 5.4 normal normal normal Normal Shaft inside AHU is open
SF AHU1 9.4 11.7 2.3 normal normal normal Less/No sweating AHU Dscaling to be done
SF AHU2 8.4 17.2 8.8 normal normal normal Normal
On/Off condition is not being showed
in graphs, Dscaling to be done
SF AHU3 8.6 14.2 5.6 normal normal normal Normal none
SF AHU4 8.4 14.9 6.5 normal normal normal Less/NO SWEATINGAHU Dscaling to be done
SF AHU5 7.8 12.7 4.9 normal normal normal Less/No sweating none
SF AHU6 7.8 12 4.2 normal normal normal Less/No sweating none

77
Differential pressure switch connected to BMS to know the filter status
Temperature inlet and outlet sensors connected to BMS
Refer BMS in appendix

80
Grills Low side:
On the low side the conditioned air is transported from the air handling unit to the area
which needs to be cooled via ducts usually made of Galvanized ions. The common ducts will be
running floor wise further branched to areas to be cooled. The point where air throw takes
place through a diffuser commonly named as grills. The grills are available in various sizes and
shapes. The commonly found grills are in the shape of circular, rectangular and square type.
The main ducts are connected to grill via a collar which is usually made of galvanized ion.
Commonly in most of the application of the low side, the difficulties found are the collar
connection from the duct to grill is improper, omission of collars itself or grills offset to collar.
These difficulties arise when CFM checks where conducted on the grills. It is a difficult to
correct these offsets in a running operation and rather it should have been corrected during the
commissioning stage itself.
Standard CFM – 556
Grill Size – 4’X4”
Area – 1.33 Sq.ft

81
Rectangular
return air grill
Rectangular
supply air grill
Square supply
air grill

82
Round diffuser
Rectangular air
supply grill
Insulated
supply air Ductcollar

83
Below mentioned is the floor wise CFM reading taken at grills on a four story
building using formulas mentioned above.
Rectangular air
supply grill
Ceiling
suspended unit
(AHU)

84
NAME GRILL
SIZE Ft
1 2 3 4 5 ARE
A
sqft
AVERA
GE
AVERA
GE
CFM
STANDA
RD
EXCE
SS
LO
W
NI
L
xxx 4'x4" 0 0 0 0 1.33
33
0 0 556 55
6
xxx 4'x4" 0 0 0 0 0 1.33
33
0 0 556 55
6
xxx 4'x4" 0 0 0 0 0 1.33
33
0 0 556 55
6
xxx 4'x4" 15
0
15
0
15
0
1.33
33
150 200 556 35
6
xxx 4'x4" 0 0 0 0 0 1.33
33
0 0 556 55
6
xxx 4'x4" 25
0
15
0
38
0
1.33
33
260 347 556 20
9
xxx 4'x4" 74
3
45
3
49
0
1.33
33
562 749 556 193
The above chart shows the CFM readings taken floor wise in an operational commercial
building. This chart is a clear indicator that the design CFM in each grill viz-a-viz is actual CFM in
each grill. Where ever the actual CFM is shown less than the designed CFM then it is
understood that there is no collar connectivity to the grill or the grill and the collars are offset.
There is also possibility that there is air loss in the duct due to minor holes or duct joints. Note
the readings are taken when AHU’s of the particular zone are in ON condition.
The problems related to AHU’s are already mentioned elsewhere. Even the AHU’s to be
checked for CFM readings at AHU supply duct.

85
APPENDIX
Automation
Automation systems are available providing a broad range of capacities to control single or
multiple parameters in the cooling system such as conductivity and blow down control, pH
control, and real-time chemical monitoring and dosing.
Blow down controllers are available from several different commercial suppliers and offer a
range of control points from simple conductivity/blow down control, to timed or meter relay
chemical dosing. Many of them incorporate water meter inputs and alarm relays if threshold
measurements are exceeded.
Blow down controllers offer continuous monitoring and control of the blow down of the tower
system. This ensures high conductivity is avoided, minimizing scaling and corrosive conditions
and minimizes excessive blow down which wastes water. Blow down control and the other
showing blow down controlled with a conductivity controller. The impact of implementing blow
down controllers, revealing conductivity rates that stay much closer to the ideal set point
compared to manual control.
More robust automation platforms are also available from several manufacturers that provide
system-wide monitoring and dosing. These platforms are scalable depending on the need, but
offer conductivity/blow down control, pH control, real-time chemical monitoring and dosing,
continuous corrosion monitoring, web-enabled reporting, and alarm relays. The benefit of
these systems is tightened control of the various control points of the water treatment
program, not only eliminating excessive water use and high cycle conditions, but also
controlling chemical residuals and treatment dosing based on real-time corrosion and scaling
indices. In trend terms, similar results to the conductivity improvements can be achieved on
chemical treatment residuals, pH set point and acid feed, biocide dosing, and corrosion
monitoring. The performance improvement real-time dosing achieves on chemical residuals,
ensuring the proper dosage of corrosion and scale inhibitors at all times and eliminating
overfeed or underfeed of charge of harmful or illegal substances.
Filtration
Filter systems are nothing new to industrial water systems, and have been used as pre-
treatment in many different applications for many years. In recent years, side-stream filtration
systems have become popular among many water treatment professionals. They function to
remove suspended solids, organics, and silt particles down to 0.45 microns from a portion or all
of the system water on a continual basis, thereby reducing fouling, scaling and microbiological
activity. This allows the cooling system to work more efficiently and often reduces the amount

86
of water blown down. However, the net impact on water consumption must consider the fact
that these platforms require back-washing to clean the filter system. The amount of water used
to regenerate the filter system should be added to the water lost due to evaporation and blow
down.
Water Treatment Plant:
The water used for HVAC system is filtered through a treatment process. The plant which treats
this is called WTP. It consists of dual media filter and a mild steel vessel with rubber lining
inside. The raw water (from bore tankers etc.) is passed through this treatment process to
optimize the parameters and rendering it fit for use into system.
Dual media filter: This is basically a vessel which consists of layers of sand and charcoal. The
dual media does a dual function of removing suspended solids in water (sand) and organics
especially Chlorine (activated carbon). Selected grades of sand are mixed together in fixed
proportion. It is supported by gravels and pebbles. This allows the filter to work using surface
filtration and depth filtration, thus allowing higher dirt holding capacity. It is externally fitted
with necessary pipe work, manual valves, pressure gauges and sampling points at the inlet and
outlet. A flow indicator, Rota meter type is provided in the inlet line to observe the flow during
service/backwash. Raw water flows downwards through the filter bed and suspended matter is
retained on the sand surface and between the sand grains immediately below the surface. The
filtered water is evenly collected by strainer on plate type bottom collecting system.
Operation on Dual Media Filter
Backwash: Water is passed upwards through the column from bottom to top and then
discharged to the drain for 10 minutes or till the effluent is clear, at required flow rate. This
results in removal of free impurities from the sand bed.
Rinse: Water is passed downwards through column. The water flows out through the bottom
collector and flows to drain. The required flow rate is maintained by use of Rota meter till the
effluent is clear for approx. 5 minutes.
The above is recommended everyday
Softener: Softener vessel consists of resin, which is golden coated. The resins have pores on its
surface. It has free ions on its surface. Generally the free ions are sodium ions which can be
replaced with other ions.
Hardness in water is due to presence of Ca2+
mg+
ions. As the water passes through softener
vessel, the ions are replaced with sodium ions over a period of time as the flow continues the
hard ions over a period of time as the flow continues, the hard ions are replaced and water
becomes soft as it continues to move faster.
Equipment details: this is MSEP pressure vessel. Externally the unit is provided with frontal
piping with necessary valves, pressure gauge and sample valve at the inlet and outlet brine

87
measuring tank and ejector for the injection of the brine solution in the tank. Internally the unit
is provided with inlet distributor and bottom collection system for collecting water during
service and distribute during backwash operation.
Operation on Softener Plant
Regeneration: When the supply of exchangeable ions within resin is exhausted, the treated
water from resin deteriorates and the resin requires regeneration-reconversion of the resin into
the operating form. In normal practice common salt ( NACL) is mixed with water and injected
for regeneration activity. For a 400 m3/hr plant 220 Kgs of salt is to be used. As a good
maintenance practice, regeneration is to be done every day.
Building Management Systems (BMS) :
The Integrated Building Management System (IBMS) supplier shall furnish and install a fully
Integrated Building Automation System, incorporating direct digital controllers (DDC) for energy
management, equipment monitoring and control, suitable for the building usage. The control
strategies shall be developed to ensure that the specified project conditions are maintained,
whilst giving due regard to minimizing of energy consumption.
Integration of the system shall mean that all the parts of the system are connected together
through software program, electronic components and hardware packaging and
communication network.
To provide maximum flexibility and to respond to changes in the building use, the system
offered shall support the use of BACnet/ LON works, Profibus and Ethernet TCP/IP
communication technologies and through DDC controller for system of electrical equipment’s,
Electrical energy monitoring FAS, PAS, ACS controls ,CCTV ,Fire Pumps, water transfer & Booster
Pumps, STP pumps, HVAC Systems, fresh air fans, smoke & toilet exhaust fans, jet fans, UPS, DG
set etc.
The system design shall utilize the latest technology in “open” network architecture,
distributive intelligence and processing, and direct digital control. The IBMS system offered
should be from the latest offerings and should be of freely programmable management and
automation stations for the full spectrum of today’s building application services.

88
DDCP :-
The out-station panel housing the DDC controllers shall be located inside the conditioned area.
Proper care shall be taken to ensure that there is no induction problem between the control
and power cables. These panels shall be IP54 and supplied by the specialist controls supplier.
The DDC controllers located inside these out-station panels shall provide the required signals to
the various equipment’s connected to these DDC controllers. The DDC controllers shall be
capable of accepting digital input signals in the form of volt-free contacts from Motor Control
Centers. The MEP contractor shall co-ordinate this activity with the IBMS contractor.
All these outstations shall be connected with a communication bus cable and terminated to the
IBMS central station. The IBMS supplier shall supply these bus cables.It shall be possible to
connect the Portable hand held terminal to be connected to any of these panels and talk to any
other DDC controllers on the same bus.

89
Relative humidity and ambient temperature:
Display of chiller connected to BMS:
DDC panel

90
Display of cooling tower connected to BMS:
Display of AHU connected to BMS:

91
QUESTIONS TO BE PONDERED ON CHEMICAL TREATMENT OF HVAC SYSTEM
Facility name:
Address:
Concerned Department and person:
1. As you understand your cooling system requirements; which option you would like to opt in
terms of quality and price associated with maintenance of the system.
 High price – High Quality
 Low price – Low Quality
 Medium price – Medium Quality
3. How are you dosing your products?
 Manually
 Based on flow
 Timer
 Automated controller
 Other
4. Is the CW system difficult to control (in terms of chemical dosage, maintaining the desired
cycles, etc.)?
 Yes
 No
 Sometimes (Please explain)
5. Are there wide variations in make-up water quality?
 Yes
 No
 Sometimes
6. Are you looking for the option of less human intervention at your site?
 Yes
 No
7. Is there a propensity for fouling/scaling?
 Yes
 No

92
8. Are there any corrosion issues?
 Yes
 No
9. Are there any microbial issues?
 Yes
 No
10. How critical is the CW operation?
 Very critical
 Critical
 Not critical
11. Does the system need to run 24/7?
 Yes
 No
12. Impacts of shutdowns/maintenance?
 Very High
 High
 low
13. Any environmental discharge concerns?
 Yes
 No
 If yes, please explain
14. How important are sustainability factors (water usage, energy usage, etc) to you?
 Very important
 Important
 Not important
15. Would you be interested in a ‘Green technology that will bring down your total cost of
operations in future?
 Yes
 No
16. Are there any other operational issues?
 Yes (please explain)
 No

93
17. Would you like a team of experts to monitor your systems 24/7?
 Yes, but at no extra cost
 Yes and I am ready to pay some reasonable amount for that
 I don’t think its required
18. If there is an upset in your system, how fast would you like to get notified?
 Within 30 minutes
 Within 30 to 60 minutes
 Within 2 hours
 I don’t need any notification
19. Would you like to receive monthly/weekly reports on the performance/health of your
cooling water system?
 Yes. Monthly/weekly
 No
20. As world is becoming so advance in terms of technology and quick response, Do you feel
that your asset performance and water analysis details should be at your fingertips?
 Strongly agree
 Moderately agree
 Agree
 Moderately disagree
 Strongly disagree
21. How important technology is for you? Would you like to use a state of the art technology
that comes at a reasonable cost?
 Yes
 No
22. You are primarily bothered regarding which type of cost?
 Maintenance and shutdowns
 Water
 Energy
 Labor
 Chemical
 Any other
23. Please list down all your key drivers (water cost, water usage, energy cost, total cost, etc)
for CW operations?
24. What is annual CW chemical usage?
25. What is existing contract type? Fixed basic agreements or variable based on actual
consumption?

94
26. In case you want install automated equipment for chemical dosing, what type of payment
option you would prefer? Would you like it on rent or complete buy-out?
 No. of rooms
 Area of SQ Meter or Sq. ft
 No of cooling towers:
 CW system volume:
 No. of chillers
 Chiller tonnage:
 Blow down (COC):
 Annual usage of water
 MU cost
 Sewage cost
 Average cost related to chemical treatment (Per annum)
 Electricity/Energy usage cost(For the chiller)
 Any sustainability/green goal:
 Annual maintenance cost
 Regulatory costs
 Labor costs
 Other critical factors
 Any other performance related measures

95
General information:
Chillers
Type Make
Capacity
(TR)
Nos
Chilled Water
Set Point
With VFD(Y/N)
Centrifugal xxxx 800 3 N/A N
Secondary Pumps Condenser Pumps
Qty Make
Flow
(USGPM)
Head
(Mtrs)
KW
With
VFD(Y/N)
Qty Make
Flow
(USGPM)
Head
(Mtrs)
KW
With
VFD
(Y/N)
5 yyy 1198 38 37 Y 4 yyy 2400 24 45 N
Cooling Towers Hours of Operation per day
Qty Make
Capacity
TR
Design
Approach
- Deg F
No. of
Fans-
Each CT
Fan KW
With
VFD(Y/N)
3 zzzz 800 7 4 7.5 N 14

96
Building energy data:
Oct-15
KWH Rs
1519600 12572782
KWH Rs KWH Rs KWH Rs KWH Rs
1618400 13516677 1653600 12920031 1654400 12896818 1580400 12364534
Jun-14 Jul-14 Aug-14 Sep-14
1622000 12655163 1525200 11953811 1546400 12141583 1542400 12109553
Nov-14 Dec-14 Jan-15Oct-14
1378400 10945281 1563200 12235577 1476800 12092471 1737600 14431550
May-15Mar-15 Apr-15Feb-15
1703600 14514277 1738400 14305375 1695600 13918760 1474400 12298743

97
Chiller energy data:
Pumps energy data:
216253 1654335 201049 1538025 196940 1506591 265418 2030447.7
267585 2047025.25 213889 1636250.85 202174 1546631.1 204129 1561587
Dec-14 Jan-15Oct-14 Nov-14
177842 1360491 239539 1832473 290160 2219724 325890 2493059
Feb-15 Mar-15 Apr-15 May-15
KWH Rs KWH Rs KWH Rs KWH Rs KWH Rs
308202 2357745 308184 2357608 293247 2243340 265103 2028038 281455 2153131
Jun-15 Sep-15 Oct-15Jul-15 Aug-15
86333 660447.5 84551 646815.2 79362 607119.3 75477 577399.05
Jul-14 Aug-14 Sep-14Jun-14
81148 620782.2 71741 548818.65 73860 565029 68762 526029.3
58212 445321.8 108925 833276.3 123801 947077.7 133041 1017764
128576 983606.4 128465 982757.3 123848 947437.2 110739 847153.4 120143 919094
Jun-15 Jul-15 Aug-15 Sep-15 Oct-15

98
Cooling tower energy data:
302586 2314783 285600 2184840 276302 2113710.3 340895 2607846.75
348733 2667807.45 285630 2185069.5 276034 2111660.1 272891 2087616
236054 1805813 348464 2665750 413961 3166802 458931 3510822
436778 3341352 436649 3340365 417095 3190777 375842 2875191 401598 3072225
Jun-15 Jul-15 Aug-15 Sep-15 Oct-15

100
Specifications for HVAC system
1 Details on Air Conditioning System Ductable Type centralised system
2 Total Capacity of Air Conditioner 3 x 800TR
3 Total Area of Air Conditioned Space
Length X Width
Height of the false ceiling from FFL
4 Type of Ceiling POP false ceiling at common area and
open to waffle ceiling at retailers and
other areas
5 Height of Building from ground floor
6 Is the Space divided in floors YES ( GF UG FF SF)
7 Maximum Number of people to occupy the Space
75000 on an average
8 Is CAD drawing available for the Space Layout
9 Temperature to be maintained
24 +/- 3 °C
10 Humidity level to be maintained 50 +/- 10
11 Wall thickness
12 Material used for construction of Wall & Ceiling POP Board –Ceiling

101
Plastered Brick Wall
13 Specify provision of insulation for the walls and ceiling Masonry Hollow block wall and POP
ceiling
14 Specify Material of insulation
15 Total Number of Electrical Appliances installed in the Space .
16 Specify the Total Wattage of the Electrical Appliances KW lighting
17 Provision of Windows in the Space
18 Specify the Number of windows
19 Specify the type of windows
20 Specify the Total area of all windows
.
21 Are Dust Collectors installed inside the Working Air
Conditioned space
No
22 Specify the Total number of dust collectors occupying the
space
NA
23 Specify the specification of each dust collector in terms of
the Air extraction Capacity
NA

102
24 Total Wattage of the Machineries Installed in the Air
Conditioned Space
2 Ball Mills: 15KW
2 Vibrating Tables :7.5KW
& OTHERS
25 Total Heating Load present in the Space
All types of leakages possible to occur from this place must be specified. There are two doors for man &
materials movement. The frequency of operation of the door will be 4times in an hour.
Other Relevant Data:
1. Bengaluru ambient conditions are
Summer- 110 deg F and 78 Deg F, mean relative humidity 24%,
Monsoon- 88 deg F and 79 Deg F, Mean relative humidity- 68%
Winter - 50Deg F and 43 Deg F, mean relative humidity - 58%
2. Total Moisture Load In the area: Maximum. 300Kg
1. Air-conditioned & dehumidified area but it is not a cleaned room application.
26 Common Floor Utility Service Available
Electrical Service Voltage: 415 ± 10%
Phase: 3-Phase + Neutral Earth
Frequency: 50 Hz ± 3%
27 Preferred Voltage At Equipment For
Control Panel 440 Volts AC

103
Field Equipment 24 Volts DC
28 Motors
 Preferred Motor Specifications
415 Volts AC
 3-Phase Induction Motor, Foot Mounted, TEFC, IP-
55 Protection, Class-F Insulation, EFF1
29 Electrical Panel
External, Remote Located Unit
30 Safety Protections  Supplier to include all Safety Protections for the
Equipment as required for the Operation and
Maintenance as per relevant CE Standard
Guidelines applicable for Industrial Gas Fired
Appliances and Safety of Electrical / Electronic
Systems & Devices associated with the Equipment.
 LOTO Provision should be Built-in for all Energy
Sources (Electricity, Hydraulic, etc as applicable)
with-in the Equipment Battery Limit.
 Platform hand railing with toe guards in case of
suspended chilling system.
 Safety protection for hydraulic hose/tube failure
31 Equipment Noise Level Limitation Should be less than 85 DBA measured at 1m distance
from source.
32 Scope Of Supply  Design and Supply of the chiller, cooling tower,
AHU and ducting system to Meet Specifications.
 Supplier Documentation along with CE Certification
for The Equipment Supplied.
 Recommendations and Price Quote for Spares to
be maintained.
 Operation and Maintenance Manuals: 2sets each of
Hard Copy and Soft Copy in CD.
 Any other accessory specifically not indicated but
essential for the Equipment Safety or Operation.

104
CONCLUSION
The Goal— an Environmentally Friendlier, Energy-Efficient, and Cost-Effective HVAC&R System
The goal is to provide an HVAC&R system which is environmentally friendlier, energy-efficient
and cost-effective as follows:
 Effectively control indoor environmental parameters, usually to keep temperature and
humidity within required limits.
 Provide an adequate amount of outdoor ventilation air and an acceptable indoor air
quality.
 Use energy-efficient equipment and HVAC&R systems.
 Minimize ozone depletion and the global warming effect.
 Select cost-effective components and systems.
 Ensure proper maintenance, easy after-hour access, and necessary fire protection and
smoke control systems.

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