Chilled Water Reset - Trane CVHE Troubleshooting Manual

Outdoor
CWS' = CWS + RATIO * (START RESET - TOD)
and CWS' > or = CWS
and CWS' - CWS < or = Maximum Reset
where
CWS' is the new chilled water setpoint,
CWS is the active chilled water setpoint before any reset has occurred
RESET RATIO is a user adjustable gain
START RESET is a user adjustable reference
TOD is the outdoor temperature
TWE is entering evap. water temperature
TWL is leaving evap. water temperature
MAXIMUM RESET is a user adjustable limit providing the maximum amount of reset. For all
types of reset, CWS' - CWS < or = Maximum Reset.
The values for "RESET RATIO" for each of the reset types are:
Reset Type
Return:
Outdoor
The values for "START RESET" for each of the reset types are:
Reset Type
Return
Outdoor
CVHE-SB-32A
Reset Ratio Increment
Range (English Units)
10 to 120%
80 to -80%
Start Reset Increment
Range (English Units)
4 to 30°F
(2.2 to 16.7°C)
50 to 130°F
(10 to 54.4°C)
Increment (SI
Units)
1% 1%
1% 1%
Increment (SI
Units)
1°F 0.1°C
1°F 0.1°C
Factory Default
Value
50%
10%
Factory Default
Value
10°F (5.6°C)
90°F (32.2°C)
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