Trane CVHG Troubleshooting

CVHE-SB-32A 94
Evaporator Refrigerant Temperature Limit
The Evaporator Refrigerant Temperature Limit is a multistage control that acts to prevent chiller
shutdown when the evaporator refrigerant temperature approaches the cutout setpoint by
reducing chiller capacity. Chiller capacity is reduced by the following steps, providing increasingly
aggressive action as the trip point is approached:
1 Limit requests for capacity increases.
2 Prohibit requests for capacity increases.
3 Initiate stepped capacity reduction.
4 Initiate maximum capacity reduction.
The purpose of this limit is to provide maximum capacity while preventing chiller shutdown due to
low evaporator refrigerant temperatures.
The Low Refrigerant Temperature Cutout setpoint is found in the Field Startup menu.
Design:
Lowest standard chilled water setpoint (CWS) = 37°F
Lowest standard low refrig. temp. cutout (LRTC) = 28.5°F
Lowest standard refrig. temp. limit setpoint (LRTLS) (28.5 + 2) = 30.5°F
Minimum differential between LRTC and CWS = 6.0°F
0.5
ERR3 = Temperature error Deg F
DS3
Hold
Forced
Unload
Limit
Loading
No
Limit
3; CTV Only
100.0*(Err3 - 0.5); CTV Only
220.0*(Err3 + 0.5); CTV Only
(#steps)
1250
-0.5
60.0*(Err3 + 0.5); RTHB Only
7; RTHB Only
30.0*(Err3 - 0.5); RTHB Only
5.0*(Err3 ); ABS Only
2; ABS Only
3.0*(Err3 - 0.5); ABS Only

Trane CVHG Specifications

General

Brand	Trane
Model	CVHG
Category	Chiller
Language	English