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Appendix B: The Chilled Water System Optimizer Commissioning view of the Properties page
Point Name/Description
...to __ degrees)
Allow condenser water temperature setpoint to rise no higher than __ degrees
Condenser Water Supply Temperature – Low Limits —This program will apply the
highest of the following methods:
NOTES
To help prevent oil migration, minimum pressure across the orifice plate, and other
low-lift issues, the condenser water temperature is given low temperature limits.
These safeties are not meant to work as primary low-limit safeties. You still need
low limit safeties at the cooling tower or the facility's local cooling tower program
The condenser water supply temperature will not drop below the highest of the
lowest limits. So, the highest limit is the governing limit.
Method 1
There are 3 low limit temperatures based on chiller capacity: Low limit temperature at
20%, 50%, and 100% of chiller operating capacity.
The temperatures are linearly interpolated between these points. If the low limit
temperature profile is not known, set the same low limit temperature for each.
Low CWS Temp. Setpoint limit at 20% Chiller capacity: __ degrees
Low CWS Temp. Setpoint limit at 50% Chiller capacity: __ degrees
Low CWS Temp. Setpoint limit at 100% Chiller capacity: __ degrees
Method 2
The condenser water temperature low limit varies based on chiller operating capacity
and chilled water supply temperature setpoint. The goal is to have enough pressure
across the orifice plate (expansion mechanism) to maintain sufficient refrigeration. This
is accomplished by maintaining a low minimum delta temperature between chilled
water supply and condenser water supply (condenser water supply temperature –
chilled water supply temperature setpoint). The delta temperature varies according to
capacity.
Low Load – Optimizer running at minimum allowable load
20% default – CWS Setpoint = CHWS Setpoint + 10°F (adj)
High Load – Optimizer running at maximum allowable load
90% default – CWS Setpoint = CHWS Setpoint + 30°F (adj)
The delta temperature varies with the square of capacity between these points. If the
low limit temperature profile is unknown, input the default. If the profile is unknown, you
can keep the defaults. If you want to disable this feature, enter 0°F for both.
Chilled Water System Optimizer v2
Installation and Start-up Guide
88
Range
D:
75°F
R:
72 to 77°F
D:
79°F
R:
75 to 84°F
D:
57°F
R:
55 to 78°F
D:
56°F
R:
55 to 80°F
D:
58°F
R:
55 to 80°F
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