# Carrier Thermidistat



## sailpe (Aug 16, 2009)

Trying to replace a non-programmable TSTATCCPRH-01B with a programmable TP-PRH01 and I can't match the old connections with the new connections.  The old connections do not match any configuration included in the original booklet.  The thermidistat runs an FV4ANF005 Air Handler.  The existing connections are as follows: S-2, B, C, W/W1, Y/Y2, G, R, O/W2.  A total of 8 wires.  The S-2 appears to match the OAT for the new unit.  All the others match something, except the old B connection.  The new unit has an O/B W2 connection and I am not sure if I should connect the old B and the old O/W2 both to the new O/B W2 connection or do something different?  Any help anywhere?


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## kok328 (Aug 17, 2009)

No, I would not make any assumptions here and it could be that the existing system is not programmable compatible.  Heat pumps and non-heat pump systems do have different wirings for the T-stat.  The B wire could be the common wire or the reversing valve for the heat pump.  You'll have to track that wire back to determine which it is.
You may also be dealing with a setup where wire colors were completely ignored at time of installation.


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