External Chilled Water Setpoint - Trane CVHE Troubleshooting Manual

External Chilled Water Setpoint

The External Chilled Water Setpoint allows a customer to change the chilled water setpoint from
a remote location. The External Chilled Water Setpoint is found on Options module terminals J9-
4 and J9-5.
UCP2 accepts either a 2-10 VDC or 4-20 mA analog input suitable for customer connection to set
the unit leaving chilled water setpoint. 2-10 VDC and 4-20 mA shall each correspond to a 0 to
65°F (-17.8 to 18.3°C) CWS range. For input signals beyond the 2-10 VDC or 4-20 mA range, an
information diagnostic is called and the active chilled water setpoint will default to the front panel.
UCP2 uses the following equations:
As generated from external source
As processed by UCP2
The following graph shows External Chilled Water Setpoint with a 4-20 mA input:
70.00
60.00
50.00
40.00
30.00
20.00
10.00
0.00
-10.00
-20.00
4 5 6
CVHE-SB-32A
Voltage Signal
VDC=.12308*(°F)+2
°F=8.125*(VDC)-16.25
External Chilled Water Setpoint with (ma) Input
7 8 9 10 11 12
ma
Degrees F
Degrees C
13 14 15 16 17
Current Signal
mA=.24615(°F)+4
°F=4.0625(mA)-16.25
Degrees F
Degrees C
18 19 20
56