Good morning!

I want to replace my ITT General Controls thermostat with a programmable one in order to save some gas.

I have an old gas in-floor furnace with the ITT thermostat Cat No. #T80AV100. (Actually the printing on the back of the thermo cover is not very good, so I am inferring that is the correct number from the other posts on this group.) Anyway, it also says "For use with Millivolt & B54M Gas Valve only".

There are two wires coming out of the wall-- both black and unlabeled.

I want to replace the thermostat with a simple type programmable thermo - just the "wake-leave-return-sleep" type is fine.

I purchased one from Home Depot saying "15 minute installation". Why does that never work out?

So this model is a Honeywell RTH221. It has all of the standard newer-type terminals -- Y, G, Rh, Rc, W.

Currently I have the two wires (in no particular order) on the Y and G terminals. The "Run"part of the program does not seem to function, but with one switch set to Heat and with the Fan set to Auto, the furnace fires and heat comes out. To my knowledge, there is no fan in the furnace.

So if this unit will indeed work in my application, which terminals do I use with my two wires?

If it will not, which thermostat will work for what I want to do?

Thank you in advance for your help!

Todd

The thermostat should say it's compatible with millivolt systems.

Rh and W should work.

Here is just one example that specificly states 20-24 VAC or 750 MV systems:

Buy Honeywell FocusPRO 6000 Programmable 1 Heat/1 Cool Thermostat, Large Screen | Honeywell TH6110D1021

I need a replacement part for my ITT thermostate model:

ITT THERMOSTAT CAT. NO. T80AV1 00B137.

Can I find this replacement part anywhere?