I swap out my OEM Coleman Mach manual slider type thermostat for a battery-operated Honeywell RTH5100B digital with auto heat and cooling changeover. I’ve done this particular upgrade a few times in the past. First I upgraded to a Hunter 42999B and then to a Honeywell Focus Pro 5000 series.
The Hunter worked well but didn’t have the auto heating to cooling switchover capability, so I changed it to the Focuspro 5000. Unfortunately, the Focus Pro 5000 failed after 2 years. It intermittently wouldn’t shut the furnace off. I had to in a pinch put the old analog thermostat back in place.
Recently I bought a replacement Honeywell digital, so I decided to video the installation in greater detail than before. I answer some of the questions I’ve received about the previous mods and explain the AAA battery operation and wiring color codes.
I’ve found some confusion has come when RVers try and follow my Coleman Mach wiring when replacing a Dometic Duo Therm. The two companies use slightly different wiring methods. The Honeywell will still work but needs a somewhat different hookup. Here is a link to a forum post with photos and a wiring diagram for the Duo Therm specific upgrade.
Disclaimer: Working with electricity can be dangerous. Performing the modifications detailed in this blog posting may void your warranty. The following is for educational and entertainment purposes only and should not be taken as instructional. If you decide to do the same modifications I’ve done then research and beware of the risks involved. I accept no liability. You have been warned! – Ray