I decided to get rid of the analog Duo-Therm t-stat by dometic in my HTT. I purchased a digital t-stat by Lux (DHM110). When I wired it up I was able to get the furnace to run on auto, the fan on the AC to run in fan mode, but the AC would not run in auto. Any ideas as to what I may have done wrong? I will attach photos of the old t-stat (wired as it came), the new t-stat, and the wiring diagram for the new t-stat. If anyone can suggest how it ought to be wired, I would appreciate it.
Thanks,
Jason
P.S. I wire up the old t-stat and everything works as it ought to...so, I have obviously not done something correctly in wiring up the new one.
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Not sure. in a residential system a heat/cool t-stat the jumper is removed. There are two transformers, one on the cool side from the ac and one on the heat side from the heat source (boiler/furnace etc.) this keeps the systems separate and from working against one another, but requires two transformers. I'm thinking that if your AC is a ducted system that runs of the t-stat then there should be a transformer. Heat is simple two wires, and that's just a switch, on/off. It's hard to tell from your pics, but it looks like green to fan on the old stat and probably a common......I just pulled up the LUX page. I'm thinking still to wire it without the jumper. It shouldn't be a problem, if there isn't a second transformer you still won't get AC and we'll have to dig deeper, but it should be a simple fix.
Ok, so yellow to Y, white to W, Blue (high fan) to G. brown is low fan, so I am assuming that won't get used since it doesn't have a two speed control. That leaves me with the green ground wire from the old unit and the red from the old unit (says +7.5). Can you tell me where they go? What is going to the RH/RC? Thank you so much for your help. I put a digital t-stat in my old PUP, but that didn't have AC.
Jason
Turns out the t-stat was bad. A little piece was broken and just hanging on inside. I bought a different one and everything works fine now. The only glitch I had was with the heat. There was a switch to select gas/oil or electric/heat pump. I picked gas and it didn't work. Switched to electric and all was well. Thank you all for your help.
Jason
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