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Chilled Water Temperature Optimizer Reset > Section 1- Chilled Water System Optimizer – Enable Conditions
(page 63)
Set the CHWS Optimizer ON Switch to ENABLED.
NOTES
This switch enables the chilled water reset portion of the program.
You can observe the changing supply water temperature setpoint as the program searches for a lower energy
consumption point.
Chilled Water Temperature Optimizer Reset > Section 3 - Manual Overrides of Chilled Water Reset - and other
Settings
First response period — first reset
1
After one response period, the temperature is raised by the amount specified in First Reset.
○
The program waits for the second response period. During the second response, the program measures
○
whether the first reset reduced the power consumption.
Second response period — second reset
2
After the second response period, the program resets the temperature again by a calculated amount.
○
If the first reset lowered power demand, then the program recognizes it is resetting in the correct
○
direction. Since the first reset raised the supply temperature, then the second reset will again raise the
chilled water supply temperature.
If the first reset increased power demand, then the program recognizes it is resetting in the wrong
○
direction. Since the first reset raises the supply temperature, then the second reset lowers the chilled
water supply temperature.
Third and successive responses — The program will repeat the above process and continue to reset the
3
chilled water supply temperature by a new calculated amount. The program continually searches for the
chilled water supply temperature that maximizes energy savings at the chiller with any increased energy use
at the pumps and fans.
Chilled water optimizer reset - Tuning
One of the most important settings in the program is the time it takes for the chilled water system to respond after
the optimization program resets the chilled water supply temperature setpoint.
The program needs to recognize if the system is using less energy after the setpoint has changed. The response
time is the period that it takes the system to achieve and stabilize at a new setpoint and allow enough time for the
total system power to stabilize at its new demand level.
Adequate response depends on each reset increment being large enough for the chilled water system to react.
The system may not recognize increments that are too small. To make the increment large enough, start the
minimum increment between 1° to 1.5°F and the maximum increment at least 1°F above that.
It is difficult to approximate the response time. If the response time is too small, the optimization program does
not get an accurate measurement of the new energy use because the demand is still changing.
NOTE It is always better to be high rather than low when setting the response time.
Chilled Water System Optimizer v2
Installation and Start-up Guide
37
Start-up and Commissioning
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