The basics about chilled water piping, pipe sizing,pump selection

1. NASEEM AP
WWW.GILLSENERGY.COM
CHILLED WATER
SYSTEM

5. CHW SYSTEM
COMPONENTS
1. CHILLER –AIR COOLED , WATER
COOLED
2. CHW PIPING
3. PUMPS
4. COOLING TOWER (FOR WATER
COOLED)
5. AHUS

6. CHILLER BASICS
1. Chilled water flows thru the evaporator .The
evaporator is a heat exchanger
2. Chiller compressor may be centrifugal,
scroll, screw or reciprocating
3. The condenser may air cooled or water
cooled
4. There can be multiple chillers in a chw
plant

7. FLOW CALCULATION
1. Common design condition is supply water 44
F ,return water 54 F temperature difference 10
F
2. Q = W*C*DELTA TEMP WHERE
Q = qty of heat exchanged (btu/hr)
C = Specific heat of fluid (btu/lb F)
W = Flow rate of fluid (usgpm)
For water
TR = FLOW* GPM* DEL T/24

8. FLOW VELOCITY
1. Too low flow rate affects chiller efficiency
2. Too high flow rate cause vibration noise &
tube erosion
3. The recommended flow rate is between 3-
12 fps

9. CHILLER EER
1. Chiller is the largest single point electriccity
user in a building
2. EER = TR * 12/kw input
3. The recommended flow rate is between 3-
12 fps
4. Chillers rarely work in full load condition (2
%) hence NPLV is very important

10. EXPANSION TANK
1. Essential to manage the thermal expansion
2. Can be open type or closed type
3. Open tanks must be located above the
highest point
4. Air water interface or diaphragm tank can
be located anywhere in the system
5. The lower the pressure in the tank the
smaller it is

11. PIPING BASICS
1. Once through & re circulating
2. Open & closed type
3. Friction loss in pipe will depend up on
 Velocity
 Interior surface roughness
 Diameter
 length
4. For long run pipes expansion joints are provided
5. the pressure in the tank the smaller it is
6. The chw Pipes should be insulated

13. PIPING BASICS
1. Piping is usually steel, copper or plastic
2. Usually closed loop
3. Cooling tower piping is open loop
4. Generally the static pressure is less than
150 psi
5. If the system is above 150 psi static
intermediate HE or chw systems are used

14. PIPING VALVES
1. 2 way or 3 way valve to direct/by pass the
flow
2. Balancing valve to control the flow
3. Gate valves for isolation
4. Globe valves for throttling
5. Butterfly valves – Isolation, throttling
6. Strainers- For filtration
7. Flexible bellows –Vibration arresting
8. NRV-at pump discharge
9. Pressure & temperature gauges

16. BALANCING VALVE

17. TRIPLE DUTY VALVE

18. GATE VALVE

19. BUTTERFLY VALVE

20. STRAINER VALVE

21. FLEXIBLE BELLOW

22. 2 WAY & 3 WAY VALVE

23. BALL VALVE

24. TAB BASICS
1. HVAC Piping testing procedure
 Pressure testing
 Evacuation
 Gas charging
2. Water pipe ling is balance with balancing
valves
3. Air side balancing done by vcd s & dampers

25. TAB INSTRUMENTS
1. Vacuum pump

26. TAB INSTRUMENTS
1. Manifold gauges

27. TAB INSTRUMENTS
1. Manometer

28. TAB INSTRUMENTS
1. Balometer