# Thermostat wire codes don not match



## ufatbasted (Oct 12, 2008)

Hello

I'm attempting to install a Honeywell programable thrmostat to replace my old mercury white rogers t stat. 


When I pull the old T stat it has 4 wires coded as follows
TC
T
RH
W.


The new thermostat mentions RH and W wires but I'm nit sure what the T1 and T wires are for. My guess is a timer as the old TStat had a timer and did not use batteries. I'm tempted to just cap them and go on with the install.

Anyone have any ideas?


Thanks


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## Katonah Medic (Nov 2, 2008)

I just replaced my old mercury stats with the same Honeywell P'gramable stat. 

My 24v system only has two wires. 

The Rh and W are the only ones you need to have it run, assuming its heat only and hot Heat/Cool. 

Check the transformer on your zone circulator and you should see only 2 wires attached.. 

This may be a late post. Let us know how it worked out for you.


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