By Brian Pursel | RVwithtito.com
If your RV has a gas/electric water heater, consider adding a spare thermal cutoff switch to your toolbox. When this switch fails, as it did during our recent drive to Arizona, the water heater will appear dead and not even attempt to ignite the propane burner.
The thermal cutoff switch is a very inexpensive safety device designed to cut power to the water heater should the temperature around the heater and burner rise to unsafe levels. This should never happen under normal circumstances, as long as the burner is functioning properly.
The thermal switch on my Dometic (formerly Atwood) water heater had fused or burnt out, as you can see in the photo. Suburban water heaters have a similar device attached to the thermostat. So, check your manual.
Even if the switch looks fine, it might be bad. Perform a continuity test using a multimeter to check it out. If there’s no connection through the switch, then it’s bad.
Don’t have a multimeter? Try bypassing the switch temporarily. With the switch removed, connect the wire directly to the thermostat (labeled T-STAT) and then turn the water heater switch back to “ON.” If the water heater comes back to life, that means the thermal switch is bad and needs to be replaced. You can pick one up online for about $10.
Note: Further troubleshooting may be needed to determine the cause of the failure and prevent future issues. Contact an RV service professional for guidance. Also, do not operate your water heater without a thermal cutoff switch installed. It’s there for a reason. Wait for a replacement.
As an avid boondocker and former vintage VW owner, I pride myself in being prepared for anything on the road, but I wasn’t prepared for this one. I now keep a spare thermal cutoff switch on hand, which should guarantee that I’ll never need it.
I hope you found this helpful. Safe travels.