Truma Water Heater Working On Gas But Not Electric

Plugging in your RV after months of inactivity, you find it works on gas but not electric power. Don't panic! Many people have had the same problem and the Truma website has a succinct explanation and an even shorter remedy. We have searched for the possible causes of this problem to bring you the answers:

These are the most common causes for your Truma water heater to not work on electric:

  1. Tripped circuit breaker
  2. Tripped reset button
  3. Defective upper thermostat
  4. Shorted or broken heating element
  5. Loose power supply wiring
  6. Tripped hi-temperature limit switch on the upper thermostat  

These are the most likely reasons for your Truma water heater not working on electric power and we will discuss them in more detail. Keep on reading to learn more information that will help you better understand your water heater.

A motorhome Giottiline Therry park in the city street, Truma Water Heater Working On Gas But Not Electric

Tripped Circuit Breaker

Truma gas water heaters that have an electrical heating component give you a backup source in case one or the other becomes unavailable. When the electric part doesn't work, a common cause is a tripped circuit breaker. How did that happen? Here's a probable scenario:

Resetting a tripped breaker in residential house

When you put away your trailer for the winter, you turned off the master switch and drained the water heater. But you forgot to turn off the water heater switch. A few months later, you take your RV out of storage, plug it in and it doesn't work on electricity. 

That's because the water heater switch, which you didn't turn off when you stored your RV, had started heating the element while you were still putting the water pump on and trying to get water through. 

Without any water in the system, the circuit breaker tripped and cut off the electricity. This is a safety measure that prevents overheating and causing damage. 

Tripped Reset Button

A tripped reset button will keep your water heater from working on electric as a safety precaution. The causes of a tripped reset button may be a faulty thermostat, loose wiring, a shorted heating element or the reset button itself has broken. 

Defective Thermostat

A  working thermostat has a continuous electrical part that can be checked by a multimeter. But the reset button of the upper thermostat can trip from overheating of the water in the tank. This overheating may be due to the thermostat contacts fusing close, a shorted element, or a miscalibrated thermostat. 

Check out this multitester on Amazon.

Bad Or Shorted Upper Heating Element

A bad or shorted upper heating element fails to heat the water before it leaves the tank. When the heating elements of a water heater turn bad, it's usually because it is covered with scale deposits from the minerals in the water.

This is a result of not cleaning or draining the water tank regularly, thus allowing the elements to sit submerged in water for long periods. 

Loose Power Supply Wiring

Before checking the power supply wiring, turn the breakers off. Then remove the junction box cover to expose the wirings inside. Reconnect any loose wires and tighten the wire nuts to ensure connection. replace the cover, turn on the breakers and check if the water heater runs on electricity.

Tripped the hi-temperature limit switch on the upper thermostat

To reset a tripped hi-temperature limit switch on the upper thermostat, simply remove the cover to get to it. the hi-temperature limit switch is covered with insulation.  Raise it a bit to access the switch and press the red button and replace the insulation and cover.

If after turning on the water heater, it still keeps tripping, it may be caused by a shorted heating element or a faulty thermostat.

A word of caution: When attempting to identify the problem and fix it, always turn off the circuit breakers for the water heater. The danger of getting an electric shock is real. After you have finished, turn on the circuit breaker to check if the electric connection is back. 

How To Fix The Electric Connection Of A Gas/Electric Water Heater 

White instant water heater installed with circuit breaker on the wall

First, make sure your water heater is not a gas-only model. It may be funny, but some people make that mistake and then conclude that the electric connection doesn't work.

So, as explained earlier, the water circuit connection tripped to prevent overheating. Fixing this issue will bring electricity back to your Truma water heater. Before attempting to fix the tripped element, it is imperative to isolate, disconnect and turn off the switch of the water heater and the main system to prevent electric shocks or burns. 

The first step is to locate the heater element and follow its wiring. This wire connects the heater to the main system. Somewhere along the wire, you see a joining point. Pull it apart gently to separate both ends. Leave it disconnected for about 20 seconds, then reconnect it. This disconnects the earth wire from the printer circuit board (PCB), allowing the heat to re-trip. 

Turn on the tap and leave the water running for a while so that it drains back up again. Wait for 20 to 30 minutes before switching your water heater back on. 

How To Reset An RV Electric Water Heater

When your water heater doesn't give you hot water, a common cause is a tripped reset button.

The reset button of an RV's electric water heater is a fail-safe mechanism that automatically cuts off power to the equipment if the water temperature reaches 180 degrees Fahrenheit. 

It is usually a red button near the thermostat and you'll have to remove a small covering panel to get to it. RV water heaters are almost always located at the exterior of the vehicle. Only the On-Off switch is inside.

Resetting your RV electric water heater is pretty straightforward. The reset button is lit up when it has tripped and all you have to do is push the button and when it clicks into place, it has reset.

But if the reset button keeps popping back out, there may be a problem other than it tripping. It could be due to a defective thermostat, faulty wiring, a grounding issue, or the reset button itself malfunctioning. 

How An RV Gas Water Heater Works

The propane gas that powers the water heater comes from the tank in the RV and connects to the water heater. An electric solenoid powered by the 12v battery has a valve that controls the flow of propane. The gas passes through a tube and when it exits, it mixes with oxygen causing the spark igniter to light up.

Gas burns in water heater

The flame that comes out will then heat the bottom of the water tank. A thermostat inside the tank measures the water temperature and turns off the switch when the water is hot enough. When the water cools down, the water heater will automatically re-ignite to heat the water again.

How An RV Electric Water Heater Works

When you're at the campground and you want to set your electric water heater up, here's what to do:

Locate the power cord of the heater. It's usually on the rear side of the exterior of your RV. Open the cover and take it out Some power cords are already hardwired into your trailer.

FIAT Ducato based motorhome Giottiline Therry T22 in the city street


Others are not but it will only take a twist and turn to attach it to the connection in the vehicle. You'll also see the requirements needed for connecting. In the US, it will be 110-125 volts and 30-50 amperes.

(If you're wondering, an electric water heater needs shore power to turn on. Your trailer's 12v battery cannot handle it.) 

Before you plug the connection to the campground's power, turn off the water heater switch and the air conditioner. 

After plugging it in, check if you have 11ov power with your microwave. If it's lit, you're good. If not, check the breakers on the fuse panel. Switch them on.

If the microwave still hasn't lit up, check the breaker at the campground connection. Switch it on if it's turned off. If that still doesn't work, contact the camp administration. 

How Much Do Truma Water Heaters Cost

What does it cost text written in the notebook

A google search shows the approximate costs of Truma water heaters.

Truma AquaGo: $1,333

Truma Therme and boilers: $256 - $500

Truma UltraStore : $500

Truma Combi 4E and Combi 6E: $1,680 - $2,046 (These are space and water heaters in one appliance.) 

Note: The US government prohibits the installation of Truma water systems and heaters in mobile homes. They are approved for recreational vehicles only.


When your Truma water heater works on gas but not on electric, the most likely cause is an electric circuit tripping and power being cut off. It's a safety measure that automatically steps in to prevent the heating element from burning up and damaging the water heater.  

Thus, always turn off the water heater switch along with the main system switch when you put away your RV for winter storage to prevent the same issue from happening.

If you found this article helpful, check out these informative posts:

11 Types of Heating Systems

Gas Heater Not Working But Pilot Light On - What Could Be Wrong?

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