http://systemcontroltech.com/ This presentation is a quick overview of the function of a chilled water system

1. Chilled Water System
Typical Operational Overview

2. Training Overview
 Purpose of a chilled water system
 Parts of a chilled water system
 Plate frame for cooling
 Plate frame for reheat
 System pumps
 Multi pump / chiller systems
 Chilled water system sequence of operation
 Condenser sequence of operation

3. Purpose of a chilled water system
The purpose of a chilled water system is to provide cold
water to air-handler equipment for the purpose of cooling
supply air to control space temperature.
 Water is cooled to a predetermined set-point that is set
within the chiller itself.

4. Parts of the chilled water system
 Evaporator
 Area of the chiller that cools the water
 Condenser
 Area of the system that pulls heat off the machine
 Cooling Tower
 Cools water from the condenser by dissipating it into the air.
 Tower Bypass Valve
 Controls condenser water flow either over the cooling tower
or recirculates it through the machine.

5. Parts of the chilled water system

6. Plate frame for cooling
A system that has a plate frame heat exchanger configured
for cooling will provide chilled water to air-handlers by
using cooler outside air temperatures to cool the water.
 Condenser water flows over cooling tower to be cooled
by outside air.
 Cold condenser water flows through plate frame heat
exchanger to cool the chilled water.

7. Plate Frame for cooling

8. Plate frame for reheat
 A plate frame heat exchanger that is configured for
reheat uses the heat generated by the chiller to provide
heat for the hot water system.
 Heat that isn’t pulled off the machine by the plate frame
is pulled off by the cooling tower.

9. Plate frame for reheat

10. System pumps
 Single pump systems only have one chilled water pump
that moves water through the chiller and air handlers.
 Multi pump systems have primary chilled water pumps
and secondary chilled water pumps.
 Primary chilled water pump flows water through the
evaporator side of the chiller.
 Secondary pumps flow water through AHU’s
 Condenser pumps flow water over the cooling tower to
remove heat from the machine.

11. System Pumps

12. Multi pump / chiller systems
Some systems have a total of four chilled water pumps and
four condenser water pumps as well as two chillers.
 Lead Lag Systems
 Allow for either pump combination to run with any chiller
 Fixed pump systems
 Allow only for a specific pump to run with a specific chiller.

13. Chilled Water System Sequence
of Operation
 Chilled water system lockout set-point
 Common set-point for economizer disable and chilled water
system lockout.
 System enable
 Chilled water and condenser water pumps start BEFORE the
chiller startup
 System disable
 Chilled water and condenser pumps run for a period of time
AFTER chiller is disabled.

14. Condenser Sequence of operation
When condenser water reaches a specific temperature the
system reacts to keep temperature from getting too hot. A
high condenser temperature can damage the machine.
Most chillers will trip on high head pressure.
 Cooling tower bypass valve (where equipped) allows
condenser water to flow over the tower or recirculate
through the machine.
 Cooling tower fans help push air through the tower to
cool condenser water.
 The Plate Frame heat exchanger (where equipped) will
also pull heat from the condenser loop.

15. Questions?