How would I wire this to a t2000? Thanks!
Oh boy, that’s an old one! Having trouble finding a diagram for that model. Do you have any of the manuals for it?
If not the best way to determine proper wiring is to look inside the HVAC at the terminals where these wires run. Your HVAC will likely have terminal labels which will match the newer T-stat. Where do these individual wire colors connect?
After I posted it I googled Lennox T90 and got a little info. I think the Lennox part is rebranded. Anyways, it’s over 50 years old! I’ll look on the HVAC side and see if I can find anything wiring wise.
I want to say on these tstats the labels match the function - G = Ground, F = Fan, so on. However, you will definitely want to confirm at the HVAC terminals. If you have any questions on the HVAC terminals please post an image of them, we’ll be happy to help.
Make sure to only remove and install wiring connections with the system powered down completely.
This is an interesting one. Having zero luck finding any details on the existing Tstat, wiring diagram, manuals, etc.
I believe the T2000 will likely work with the furnace, but this may be a case where you want to consult an HVAC specialist.
Can you confirm whether the same wire in terminal “F” is looped around and jumped to terminal “G” and that only four conductors are present? It appears that way in the photo but I want to be sure.
I’ll look more closely when I get home but I think what you said above is correct. “Can you confirm whether the same wire in terminal “F” is looped around and jumped to terminal “G” and that only four conductors are present”
It’s supposed to be very cold where I live this weekend so I’m going to hold off messing around with it for fear of breaking it.
I’ve looked for a few hours online trying to find a wiring diagram for the thermostat and HVAC with no luck as well.
What are you thoughts if “terminal “F” is looped around and jumped to terminal “G” and that only four conductors are present” is correct?
I already have a call into a HVAC guy 
This is the thermostat by the way.
http://www.ebay.com/itm/like/201749117453?lpid=82&chn=ps&ul_noapp=true
This forum has what the letters on the thermostat may mean:
http://www.thermostatforums.com/showthread.php?925-1960-s-itt-general-control-thermostat
F = fan = G
C = Cooling = Y
H= Heating = W
V= power = Rh, Rc
What are you thoughts if “terminal “F” is looped around and jumped to terminal “G” and that only four conductors are present” is correct?
It would mean that the only information I can find about those terminal labels is unfortunately likely not correct.
F = fan = G C = Cooling = Y H= Heating = W V= power = Rh, Rc
This is mostly what I found as well, actually, and it makes sense. Alarm.com support similarly had trouble finding any details but came to the same conclusion. They do recommend contacting an HVAC specialist before doing anything though due to lack of documentation. I suppose there may not be an actual ground wire present.
If we could get a shot of the rear of that manual in the ebay listing it likely has wiring diagrams on it.
Thanks for all the help!! I’ll likely reach out to an HVAC guy next week.
I dug these up but the resolution is not great. Are the helpful?
Is it possible to post clearer pictures? These are a bit blurred.
After much digging I found this!
Thank you for posting. That would confirm the description above:
F = fan = G C = Cooling = Y H= Heating = W V= power = Rh, Rc
So would my existing thermostat wiring work with the T2000?
Alarm.com indicated that the T2000 should work with the HVAC you have, yes. Be sure to remove all power from the HVAC before switching any wiring. Follow the wiring description above. The T2000 has a jumper connecting Rh and Rc, so just wire V into Rh. The rest should be swapped one for one based on the above description.
One last question, I read in one of the threads that battery power is recommended even though it’s (t2000) connected to low voltage. Am I remembering that correctly?
Thanks so much!
No, battery power is not recommended for thermostats. It is recommended to use the 24VAC power from the HVAC as this will allow the Tstat to function as a repeater and be always listening.
With battery power thermostats function in Flirs mode, which is a power saving mode and generally requires closer proximity to the panel or more assistance from repeating nodes.
A C wire would be required to receive power from the HVAC, and no C wire is present on your existing thermostat, so keep in mind wiring one for one will result in battery only operation. Sometimes installers will run a fifth conductor anyway though, so it would be goo dto check if there is an unused conductor if you intend to power it off of 24VAC.