Monday, December 4, 2023


My Suburban water heater doesn’t work on 120-volt power. Does it need a second switch?

Dear Dave,
My Suburban water heater doesn’t work on shore power, or any other 120 power source. I made sure the switch was on at the water heater. I also verified I had power at the outlet that the water heater is plugged into and that it was actually plugged in. The only obvious thing I see is that there is no switch for the water heater to run off of 120 on my control panel. The only switch is for gas operation. Do I need the second switch? I looked on the Forest River website, but it’s of no help, and the dealer is backed up for months. Can you help?? —Kevin, 2021 East to West Della Terra 271BH

Dear Kevin,
Your Suburban water heater has a switch on the face of the water heater in the lower left. This switch provides 120-volt power to the heating element. This photo shows the switch with tape over it to ensure it is in the off position when sent to the dealership.

You should also have a switch inside the rig that turns the water heater on and off in either mode. If the switch on the actual heater is off, turning the inside switch on will send 12-volt power to the module board and it will start the lighting procedure for the propane mode of operation. If the switch on the unit is on, turning the inside switch on sends 12-volt power to the module board, as well. However, it will then allow 120-volt power to go to the heating element, which is located just to the left of the drain plug behind the black plastic cover.

120-volt power is supplied to the water heater from the distribution center with a 15-amp circuit breaker. Since you verified there is 120-volt power to the outlet, the circuit breaker is on. Next, check to verify you have 120-volt power to the switch on the water heater. If yes, check for 120-volt power at the thermostat. There is a high limit switch on the black rubber cover just below the relief valve. The right side button is for 12 volt and the left is 120 volt. These can be reset by pushing them in and feeling a click. If you have power to the switch, check for 120-volt power at the heating element. You can check the heating element with the power off and check for continuity and it should have an Ohm reading of 10 Ohms of resistance.

Remove the element and check for calcium buildup, an expanded element, and cracks. The most common issue with heating elements is starting the water heater on the electric mode without water in the tank, which will ruin the heating element. This is common in the spring when bringing the unit out from storage and not realizing the switch on the unit is in the on position.

 You might also enjoy this from Dave 

Why does RV’s water heater work on LP but not on 120 volts?

Dear Dave,
Regarding my RV’s water heater, the gas part works good after I replaced the disc thermostats but I cannot get the electric to work right. It’s an Atwood 10-gallon unit. I have replaced the solenoid switch and the heating element, but it’s still not working. —Brad, 2006 Monaco Monarch

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Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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Dave Solberg
Dave Solberg
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. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.



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Connie Anderson (@guest_229178)
8 months ago

My Rvs water is scorching hot. The thermostat has been changed. The anode rod has been changed out. Can it be the Suburban module Board that makes the water 130 degrees. It only started to over heat 2 months ago. The tank has been cleared of all sediment too. We flushed it out…..Please help.

Last edited 8 months ago by Connie Anderson
Thomas D (@guest_226343)
8 months ago

Most people don’t know about the switch on/ in the heater. Isn’t easy to see. But when mine didn’t work it had a loose connection and had burnt up. Had to remove it to see.

Tom Herbert (@guest_226340)
8 months ago

This same thing happened to me last summer with my 2016 Forest River Cedar Creek 34RL with a 12 gal. Suburban water heater. For me it was a fried wire on the 120 volt limit switch under the black cover. Looked like the wire grounded on the frame of the water heater. Happened to have a spare switch as it was only about a $12 part. Relatively easy replacement as well as bending the frame away from the switch. No problems since. My rig doesn’t have a water heater switch inside other than the one for the gas part of the water heater that stays off unless I’m using gas.

Dave Telenko (@guest_226328)
8 months ago

Hey Dave, I bet it’s that tape over the 120VAC switch on the water heater. Might even be instructions supplied with the unit, but most people never take the time to read them! I’ve been guilty of that myself.
Thanks for the great information

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