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Appendix B: The Chilled Water System Optimizer Commissioning view of the Properties page
Point Name/Description
Minimum and Maximum Reset Increments & Program Reset Gain
Each response period, the program determines the next reset signal that lowers energy
demand most effectively. The program outputs a reset signal between 0 and 10 (deg) (0
(deg) is no reset or coolest temperature, 10 (deg) is the maximum or warmest
temperature).
EXAMPLE The program is producing a 5.4 (deg) reset signal. The next time it resets, in
order to minimize energy use, it either adds to the signal, by raising the temperature, or
subtracts from the signal, by lowering the temperature. Each reset increment falls
between the minimum and maximum allowed reset increment.
The actual reset value is based on the reset gains and program measurements of the
curve profile. If the program is currently producing a 5.4 (deg) reset, and the next reset
increment is determined to be 1.1(deg), thenthe next reset output will be (5.4 (deg)
+1.1 (deg)) = 6.5 (deg). This will be converted to the actual setpoint in the chiller
program.
NOTE The reset increment should be large enough for the system to register the reset
temperature and react to it – but not so large that it creates instability. If the
temperature increment is too small, the system won't experience enough temperature
change to determine if it saves energy.
Minimum Reset Increment: __ (deg) (output units: 0-10) — The minimum allowed
output increment for each response interval.
EXAMPLE If you set this value to 1.0 (deg), the program resets no less than that for
each increment. This does not necessarily equal the actual reset at the chiller,
which may have a range of 42 to 54°F. Unless the 0 - 10 (deg) signal is exactly the
10°F temperature range, the minimum increment may not equal the actual
temperature increment. With a range of 42 to 54°F, each reset degree is (54 -
42°F)/10 = 1.2°F.
Current reset increment is: __ — Displays value.
Maximum Reset Increment: __ (deg) (output units) — The maximum allowed output
increment for each response interval.
EXAMPLE If you set it to 1.5 (deg), the program resets no more than 1.5 (deg) for
each increment. As described above, this does not necessarily equate to the actual
reset at the chiller.
Reset Increment Coarse Gain — (1=min to 10=max) Determines how large each
reset increment will be. The program applies the gain to various measurements of
the efficiency curve, and determines the next increment size. The larger the gain,
the larger the increment. However, no matter how small or large the gain, the
increment can be no less than the minimum increment and no more than the
maximum increment.
Reset Increment Fine Gain — (0=min to 10=max) A fine gain that is added to each
increment. It can be combined with the above gain to configure the best gain
applied to each increment.
More is described about how to set up the gain in the Start-up and Commissioning
(page 31) section.
Chilled Water System Optimizer v2
Installation and Start-up Guide
78
Range
D:
1 (deg)
R:
0.5 to 1.2 (deg)
D:
2 (deg)
R:
1.5 to 2.5 (deg)
D:
5
R:
1 to 10
D:
0
R:
0 to 10
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