Installing an adjustable water heater thermostat

Like many of you who own RV’s, Steve has a list of small projects to complete on Betsy this winter, and he’ll write a short post about the ones we think might be helpful to others.  Here is one he’d like to share. 


If your RV has a washer/dryer and/or dishwasher this post is probably not for you, as those machines require very hot water to do their job properly.  But you may want to read on if your hot water use is limited to showers, manual dish washing and other day-to-day needs.

This installation was performed on an Atwood water heater, and the adjustable thermostat kit (about $30) was advertised as universal for all Atwood units.  It consisted of the adjustable thermostat, a retainer and spring and two wire sections with terminals that adapt the new thermostat terminals to the existing wiring.

With our recent water heater/plumbing repair completed, we were once again getting scalding hot water at the taps.  I thought it made sense to install an adjustable thermostat as a way to save some propane and electricity.  Why heat the water to a higher temperature than we needed on every cycle?



Photo grabbed from Amazon

After cutting off half of the foam cover and removing the old thermostat per the instructions, the only slightly challenging task was to get the retainer/spring assembly tabs pushed under the front panel so the new thermostat was seated flat against the water heater tank.  The final step was inserting the two adapter wires between the existing wires and the new thermostat.

That was it for the installation.  Settings on the thermostat range from “A” to “E” (a bit strange), and I had read that each letter corresponds to about 10º of temperature reduction with “E” being the hottest.  The factory-installed thermostat had supposedly allowed the shutoff to occur at about 150º.


The unit was set to “C” when I installed it, and after experimenting for a couple of days I found that “B” was about right for us (which would equate to about 120º, but I haven’t measured it yet).  When I turned the hot water tap all the way up it was no longer scalding hot, but hot enough for a comfortable shower on a cold day (which Prescott, AZ was amply supplying at the time).

Now I can set the temperature up or down with a screwdriver if I need to, and I’ve already noticed that the water-heating cycles are shorter.  For about $30 and very little effort I think this modification will pay for itself over time, and it would be especially beneficial to folks who primarily use propane to run their water heater.