A/C change / heater thermostat

[ocala guy]

I may be changing the Dometic A/C on my 21 C 2017. Was wondering if anybody has done this and how did you address the thermostat for the heater? The current digital Dometic one controls the A/C and heat. If I go with Houghton it does not need a wall mounted thermostat, however, I will need to change the one for the heater. Thanks

[rubicon327]

Could you not just leave the existing Dometic thermostat to run the heater? Does it need an A/C hooked up to run properly?

[Vermilye]

Originally Posted by rubicon327

Could you not just leave the existing Dometic thermostat to run the heater? Does it need an A/C hooked up to run properly?

Unfortunately, the Dometic thermostat that Escape uses to combine the AC & furnace in one unit requires a module that is located in the AC. The current thermostat has 3 wires - a ground, +12V, and a "sense" wire running to the module in the AC. While it may be possible to move the module to a new location & use it to control only the furnace, I don't know if that is possible.

If not, you would need to rewire the run between the thermostat location & the furnace to provide 2 wires & change to a furnace only thermostat. Most home type thermostats use 24V AC from the furnace to operate - won't work with the trailer system. There are a few digital thermostats that have an internal battery, or you could use the Dometic manual "clunk" version.

[ocala guy]

Thanks for your info. The control box used to handle the a/c and heater is not mounted in a very good location. It just hangs inside of the return air of the ac unit. To move it to a better location would be an issue. Escape sells trailers with no a/c and just heat. I wonder how they address that, I believe they just run 110 to the max fan area, but I don't think any other wiring with it.

[rubicon327]

Originally Posted by ocala guy

Thanks for your info. The control box used to handle the a/c and heater is not mounted in a very good location. It just hangs inside of the return air of the ac unit. To move it to a better location would be an issue. Escape sells trailers with no a/c and just heat. I wonder how they address that, I believe they just run 110 to the max fan area, but I don't think any other wiring with it.

You are correct that “A/C Ready” is just a 12 gauge wire from the power center to the rear roof opening area. If you only get furnace from the factory you get a cheap mechanical thermostat. Many of us have changed these to digital. It is only two wires from furnace to the thermostat. If you can intercept these wires leaving the furnace you should be able to make something work pretty easily.