# X wire on old thermostat



## Jellybean (Mar 29, 2008)

I have a heat pump with emergency heat function. Changing the old thermostat to a Rite Temp 8010. All the connections corresponded just like the installation manual said. Only question I had was the old thermostat had a black wire connected to an X terminal. The new thermostat, which has 2 AA batteries, said to tape off the X wire from the old thermostat. I did that and everything seems to work fine (didn't check AC today though). I also pulled the panel off the heat pump unit in the basement and the black wire in question above is connected to a C terminal (apparantly the common side of the 24 VAC transformer? I thought I read somewhere that I could go ahead and connect that black wire from C in the basement to C on the new thermostat and extend battery life? Or should I just quit while I'm ahead and leave well enough alone? Thanks.


----------



## biggles (Jan 1, 2008)

if the new stat info calls for the C from the furnace hook it up for the comon sidde of the TR so you have a true 24V at the subbase.the newer stats with the larger LED screens and more digital options calls for a solid 24Vs the battery s to keep the stat info constant during a power failure until the power comes back up.


----------



## hvacdad211 (Mar 30, 2008)

you can hook up the wire to the c terminal on the tstat and then get rid of the batteries .


----------



## Jellybean (Mar 29, 2008)

Thanks for your help. I appreciate it.


----------

