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Ask Dave: Why am I not getting 120-volt power to the water heater?

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. Today he discusses troubleshooting a water heater.

Dear Dave,
I am not getting AC voltage to my Suburban SW12DE water heater. I have Ohmed out the wiring from the input to the switch through the element. It seems to be OK. Element has 10.6 ohm resistance. I am stumped. —Kenneth

Dear Kenneth,
Your Suburban SW12DE is a 12-gallon water heater that runs on propane or 120-volt electrical power. The first thing I always check in this type of situation is, does it work on propane? For any appliance that has dual power sources, one should always check both operations. This will eliminate the module board.

Next, check the emergency cut-off and/or high-limit switch. Your unit has a switch that shuts off if the temperature gets over 180 degrees.

The standard temperature of your water heater is 130 degrees. If it goes over 180 degrees the reset button will trip and needs to be reset.

Make sure there’s water in the water heater before starting it up after storage

The most common issue with units that feature a heating element is starting the water heater up after storage without water in the tank. This will overhead the unit and burn out the heat element.

Verify you have 120-volt power to the rig by either shoreline power or the generator running.

Check the circuit breaker in the distribution center.

Turn on the power switch inside the rig and the one located at the front of the water heater in the lower left. This supplies 120-volt power to the high-limit switch and thermostat.

With your multimeter, check for 120-volt power at the thermostat and heating element. My guess is your thermostat is either tripped or bad, since you have checked the resistance at the heat element.

Read more from Dave here

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##RVDT1722

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Daniel Opstedahl
23 days ago

check the relay for water heater in the EMS (energy management system) panel if you have one. It is a switch and mine failed on 2008 bounder MH 7 years ago. did trouble shooting on all suggestions Dave made to no avail. Three months ago i discovered the relay and it was failed. bypassed it (got a new one now) and the electric side of water heater started to work. Yay. DanO

Alpenliter
24 days ago

Chances are he missed the on/off switch hidden on the lower left face of the water heater.

Chris
24 days ago

If the gas works, research how to get to the reset switch on the water heater.

The reset switch on my Winnebago is almost impossible to access. It is on the rear of the water heater, up against an interior wall, but there is no access port. Google for more information. One person went as far as cutting an access port in the RV, which is how it should have been designed in the first place.

Recently, my water heater would not work on AC but did on gas. The repair facility put in a new water heater, for over a thousand dollars. In retrospect, I’m convinced that they didn’t try the reset switch. (I have no evidence one way or the other.) If you find yourself in the same situation, be sure to ask if they tried the reset switch.

Tommy Molnar
24 days ago
Reply to  Chris

“Factory trained expert repair”?