So I've looked and looked and can't seem to find anyone else with my particular wiring weirdness. Got a nest thermostat today and learned that my heat pump/gas furnace combo is a bit more of a complicated install than I realized. I went through the thing to get a quote from a "nestpro" but I'm also still determined to figure out this dang thing on my own. If only so I can understand it. What I've got is a BAYSTAT240A "Weathertron" thermostat controlling a Trane 1200 XL heat pump and a 90E gas furnace. In the thermostat I have the following wires: Red to R Brown to T Orange to O Green to G Yellow to Y Black to X2 Blue to B White wire shoved back in the wall Wierd little bridge thing between U and W terminals but no actual wires connected to them F with no wires connected to it In the furnace panel there's Yellow to Y White to W Red to R Green to G Blue to C (Common?) Then not connected to anything it seems are orange, brown, and black wires. What I thought was that the heat pump should be for cooling and heating down to a certain temperature where it can't keep up and so the furnace would kick in? Right? I'm not entirely certain how it actually works as I was a teenager when the house was built (2001) and my grandmother isn't entirely clear on it either. Until today my knowledge of this system ended at the switches on the thermostat and changing the filters regularly. Here are some pictures of the current setup. [url]https://imgur.com/lL3nsRQ[/url] - Current thermostat setup [attach]96845[/attach] [url]https://imgur.com/u5ZGTYc[/url] - stray wires next to the furnace wiring panel [attach]96846[/attach] [url]https://imgur.com/QJfEi1p[/url] - Furnace wiring panel [attach]96847[/attach] [url]https://imgur.com/7DhM78S[/url] - Wires in the heat pump outside - [attach]96848[/attach] I'm not sure if there's a panel in there somewhere but it started raining before I could check the other side of the unit. I also have the install guide for the furnace with lots and lots of fun diagrams that make no sense to me but I can post if needed. Help. Please. Thank you. :(

Hello all, I found a similar thread here but it ended without resolution: [url]https://www.doityourself.com/forum/thermostatic-controls/590495-trane-nest-install.html[/url] I have a Trane XR15 A/C and Trane XE80 Air Hander. They are operated via a Honeywell 69-1815EFS-09 thermostat. I am trying to replace the honeywell with a Nest 2 thermostat. The existing honeywell thermostat has a communications interface device. I already know this system is incompatible with the Nest. Thus, I've attempted to bypass it and Nest reports no power to Rh (or Rc if I switch wires). I thought this would be an easy fix. Any thoughts on what I am doing wrong? My goal is to use a "smart" thermostat (energy savings) and to control temperature wirelessly. I am a relatively new homeowner and this system is pre-existing. Thank you I've included pictures of the existing wiring up close and a bit extended. I took the interface module cover off. I also took a picture of the existing thermostat hook up. Lastly, I took a picture of my finished product. The nest did not like it (said no power to Rh) When I attempted to install the Nest I put: White - W Yellow - Y Blue - C Red - Rh (and tried Rc) Green - G [attach]96995[/attach] [attach]96996[/attach] [attach]96997[/attach] [attach]96998[/attach]