Dometic RV Water Heater Not Working on Electric or Gas

We can only imagine the bewildered look of RVers when they discover their Dometic RV water heater not working on electric or gas. The most common culprit behind such an issue is an open winterizing valve.

Other possible reasons include a failing thermal cutoff switch, a faulty thermostat, a blown fuse, wiring and gas line issues, and a defective thermocouple.

Please continue reading to understand why a Dometic water heater is not working.

Fix Common Issues with Dometic RV Water Heater

The following troubleshooting guide shows common issues occuring with a Dometic RV water heater. We recommend checking these concerns before calling a professional.

Issue 1: The water heater doesn’t work on electricity, only gas

Three factors can explain why a Dometic water heater works on gas but not electric.

1. A defective or failing thermal cutoff switch

A malfunctioning switch prevents the Dometic water heater from turning on. This component is a safety mechanism  that prevents electrical elements from overheating by interrupting electricity.

To see if the thermal cutoff switch is working, follow the steps below:

• Switch the multimeter to the Ohm setting
• Unplug all the wires connected to the cutoff switch
• Touch the switch’s terminals with the multimeter’s two probes
• If the reading is OL, the thermal cutoff switch must be replaced

2. A problematic thermostat

Thermostat issues can manifest in many ways, including the water not getting hot enough, too slow to recover hot water, and zero hot water. The instruction below will help you determine if this is indeed the case:

• Turn off the water heater
• Switch the multimeter to the lowest Ohm resistance
• Unplug all the wires connected to the system
• If the multimeter’s reading is “1”, replace the thermostat.

3. An issue with the water heater’s Compass Connect controls

If both the thermal cutoff switch and thermostat are working, but the water heater still fails to turn on, Dometic’s Compass Connect technology is the most likely culprit.

Unfortunately, this system is beyond the reach of ordinary homeowners. Hence, your only recourse is to seek professional assistance. The problem is that technicians well-versed in this technology are a rare breed.

Issue 2: The water heater doesn’t power on.

Another Dometic water heater issue RV owners face is the appliance not lighting. The causes vary across water heater types (i.e., gas and electric).

1. Blown fuse or tripped circuit breaker

Electric water heaters, including Dometic, require a dedicated circuit breaker to ensure proper and safe operation. Unfortunately, the breaker could trip because of overloading.

Overloading, grounding, and short circuits can also blow the water heater fuse, causing it not to turn on.

Hence, you might want to assess the circuit breaker and fuse for integrity. You can reactivate a tripped circuit breaker or replace a blown fuse.

2. Circuit board problems

Some electric water heaters have electronic igniters controlled by a circuit board. You can consider this issue if the fuse and circuit breaker are intact, yet the water heater doesn’t turn on. Replacing the circuit board should be able to resolve the problem.

3. Gas supply blockage

If the Dometic RV hot water heater is not working on gas but does on electricity, you may have a clogged pilot tube or blocked gas supply line. Fuel flows through these components to ignite the pilot tip and burner.

Unfortunately, we don’t recommend a DIY approach to gas issues. You’re safer with a pro.

4. Igniter issue

Listen for a clicking noise when turning on the Dometic water heater. There’s a good chance your ignition system is defective if you hear a click but the pilot doesn’t light.

You can try manually relighting the pilot by pressing a button or igniting the pilot with a BBQ lighter wand.

Issue 3: The water heater doesn’t stay powered on

You are successful in lighting the Dometic water heater. The problem is it dies out after a while. What’s causing this issue, and how do you solve it? Read on to find out.

1. A problem with the thermostat control valve

The thermostat control valve is a temperature-sensitive and –activated mechanism that “turns” on the heat if it senses the water temperature drops below its set point.

Replacing the thermostat control valve should fix the issue of the Dometic water heater not staying lit. We recommend a licensed technician perform this task because the component can be a safety hazard if you’re unsure of what you’re doing.

2. Thermocouple issues

Suppose the TCV is functional or replacing it doesn’t solve the problem. In that case, there might be an issue with the thermocouple – a safety device that keeps the gas line open to light the pilot and ignite the burner.

If this component fails, the pilot won’t stay lit. Replacing it should solve the problem. However, you might want to check the thermocouple’s placement on the pilot tube beforehand. Repositioning it sometimes helps.

Maintain and Prevent Future Problems

Fixing common Dometic water heater problems is only part of the equation. Taking proactive steps to prevent future issues is necessary. Here are some tips to maintain your motorhome water heater.

• Regularly inspect the water heater components, including electrical connections, burner, combustion chamber, pilot tube, and ignition mechanism.
• Check for signs of leaks, rust formation, frayed wires, and limescale buildup.
• Assess the components for debris, soot, and other organic material.
• Ensure there’s no leak in the temperature & pressure relief valve.
• Drain, clean, and flush the Dometic water heater periodically.
• Inspect the thermostat, heating elements, and other electrical components.

Conclusion

A Dometic RV water heater not working on electric or gas can be a sign of a severe problem in the water heating appliance. If you don’t fix it, you’re at the mercy of cold showers and less-than-sanitary dishes. Unfortunately, it can also undermine your RVing adventures.

The best approach to solving such an issue is to start with the simplest possible explanation. However, we must emphasize this is only feasible if you understand the user guide. Troubleshooting a Dometic RV water heater requires eliminating the plausible causes one at a time.

Call the pros if all else fails.