Our 2011 Keystone Cougar trailer came with a manual slide style thermostat controlling the RV furnace and the air conditioner and fan. It was a total pain to find an exact temperature with, and the range between turning on and off was too broad. We were ending up too cold then too hot all the time.
So, early on I upgraded to a digital thermostat in the form of a Hunter 42999B which at the time was a popular mod. The Hunter performed well, and we enjoyed being able to set the exact degrees and the much tighter temperature range offered.
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
Lately, though I’ve been hearing of newer models out there, that will work in the RV and provide a few features lacking in the Hunter model. One, a backlit display so we can easily adjust it at night. Two, auto switch over between heating and cooling with dual temperature controls. The Honeywell FocusPRO 5000 (TH5110D1006) fills the bill.
For a thermostat to work properly in an RV, it has to be either specially designed to be powered off 12 VDC (most home units use 24 VAC) or by onboard batteries. In the case of the Honeywell FocusPRO 5000, it uses a pair of AAA alkaline. The Hunter we had used AA, and they lasted about a year.
Installing the Honeywell FocusPRO 5000
The installation was extremely straightforward. Since I already had done the upgrade to the Hunter I knew what wire was what in my rig. The color coding on the Honeywell matched up so just a matter of connecting the wires to the screw terminals.
One thing I did change this time around was the hi/lo fan toggle switch. This switch toggles the fan speed on the air conditioner. It’s required to maintain that feature as the neither the Honeywell or the Hunter had that option. So without the switch, you would have to choose one or the other speed. For the Hunter, I carved out a piece of its case. For the Honeywell, I decided to mount the toggle switch in the wall beneath it.
Once the thermostat is installed and up and running, there are a few settings to go through. I set the AC compressor protection off time down from 5 minutes to 2, adjusted the unit for auto changeover (manual it the default) and set temperature range stops for heating and cooling. (See installation manual for complete details)
Video Detailing the RV Thermostat Upgrade
I’m pleased with this little upgrade and the extra functionality provided. Now we can set our desired hot and cool temps, and the thermostat takes care of the rest.
Update July 2019 – Detailed installation post and video of the Honeywell RTH5100 thermostat