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RV Water Heater Troubleshooting & How To Fix It

RV water heater

How to Fix Common RV Water Heater Problems

RV water heater troubleshooting is relatively simple if you understand the basic operation of the unit. While a book would be required to cover everything that can go wrong with an RV water heater, this entry will serve as a brief overview of water heater operation and the most common and easily solved problems.

After all, camping without hot water is not any fun. By knowing the basics of RV water heaters in advance, you might just save yourself the headache of breaking camp and heading to an RV repair facility.

“It’s definitely not impossible to live without warm water, but it can sure be inconvenient if you haven’t planned for it. Most people would probably agree that stepping into a cold shower is definitely one way to wake up on the wrong side of the bed, especially on those already chilly summer mornings.”

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Says Art at RV Care

Disclaimer: Working with propane and electricity can be dangerous. Take your RV to a service center if you are not familiar with safely working with these two energy sources.

Types of RV water heaters

This entry will focus on the most common types of water heaters found in RVs, which contain a tank primarily heated by the burning of propane gas. Some will also contain an electric element which can be used in place of propane or used in conjunction with propane to heat water faster.

  • Manual Gas Valve: As the name suggests, the gas valve that controls the propane is manually activated. The valve is located on the exterior side of the RV and utilizes a standing pilot light which has to be lit from the outside of the RV.
  • DSI (Direct Spark Ignition): This is the most common type of water heater in today’s RVs. These models allow the user to flip a switch inside the RV to light the propane burner on the water heater. Click here for an explanation on how DSI works.
  • Electric: As noted above, RV water heaters can also be equipped with a submerged electric element that can be used to heat the water within the tank.

RV Water Heater Troubleshooting

Before you can attempt to fix your RV water heater, you need to determine why it is not operating as designed.

Start by verifying the problem is not an issue with supply. Here is what you will need to check:

  • Pressurized freshwater is reaching the inlet of the water heater. This is most easily tested by opening the pressure relief valve located near the top of the water heater. If water comes out, it is not a supply problem. Use caution when opening the valve as scalding could occur if hot water is present.
  • Propane: Make sure your propane cylinders are turned on and other appliances are operating correctly. Next, try to light the water heater and look or smell for any signs of propane coming through the gas valve. Finally, if you are unsure whether you have propane coming to the water heater (with no nearby ignition sources present) you can “crack” open the gas line where it enters the gas valve to check for propane escaping the gas line by smell, sound, or using soapy water sprayed on the fitting. Secure the fitting when done and check for leaks using soapy water sprayed onto the fitting. Click here to see what can happen if you leave a gas line open.
  • 12 Volts DC (aka battery power): If you have a DSI water heater, you will need to verify that a full 12 volts DC is reaching the water heater when the water heater switch is turned on inside the RV. A wiring schematic can be found in the water heater owner’s manual.
  • 120 Volts AC (aka shore power): If your water heater is equipped with an electric element, verify the switch(s) that controls the electric element is turned on and 120 volts is present by safely using a volt Ohm meter.

RV Water Heater Repairs

If you didn’t find a supply issue using the above steps, here are the most common problems with RV water heaters and how to hopefully correct them.

Manual Valve Water Heaters

Problem: Pilot won’t stay lit

A) Make sure the thermocouple is free of soot, centered in the flame of the pilot light, and is screwed in tightly to the control valve.

B) Remove and clean the pilot burner, pilot orifice, and tube. Note: Only clean an orifice with compressed air as drill bits and other abrasive items can enlarge the opening.

Click here to learn how to test a thermocouple using a volt Ohm meter.

If the above two steps do not correct the problem, you likely have a bad thermocouple or control valve. Gas valves are not serviceable. Repair should never be attempted.

Problem: Pilot stays on, but main burner won’t light

A) Make sure the valve is turned to the “On” position.

B) Check for obstructions in the orifice – clean if needed.

C) Pilot is on, but no gas flows from the valve when turned to the “On” position.  Valve most likely needs replacing.

DSI water heaters

Problem: Won’t ignite (Nothing happens when the switch is turned on inside the RV)

Check to make sure 12 volts is reaching the control board.  Voltage can be interrupted by the thermostat or high limit switch which has a reset button.

A) When 12 volts reaches the board (assuming the board is properly grounded), three things should happen: 

1) The board will begin discharging high voltage to the igniter.

2) The board will send 12 volts to the gas valve.

3) The board will sense if a flame is present and if so, continue sending 12 volts to the gas valve. If no flame is sensed, the board will shut power off to the gas valve.

If items 1 and / or 2 do not occur, check the fuse in the board, if so equipped. If the fuse is good, the board is most likely defective and needs replacing. Most RV service centers have a circuit board tester that can check all three functions of the board.

Problem: Sparks appear at the igniter, but won’t ignite

A) No gas from valve – verify 12 volts is reaching the valve and it is grounded.  If 12 volts is present, try lightly tapping the valve as it may be stuck, otherwise the valve most likely needs replacing.

B) Valve opens, but no gas to burner. Check for obstructions in the orifice.

Problem: Ignites, but won’t stay burning

A) Check the wiring connections for the igniter as the signal that a flame is present may not be making it back to the board.

B) Make sure the igniter is centered and can “sense” the flame. Adjust if needed.

C) Clean soot or corrosion off the igniter.

Both manual and DSI water heaters

Problem: Main burner “roars” excessively, causes soot around the exhaust port, or has a yellow flame

A) Make sure burner tube is free of obstructions like spider webs, wasp nests, etc. Clean as needed.

B) Air / gas mixture is incorrect. Adjust the air following the manufacturer’s instructions until the flame is blue in color.

Electric Element

Problem: There is no hot water when operating the water heater solely on electric

A) Check to make sure 120 volts AC is reaching the element. Voltage can be interrupted by the thermostat or high limit switch which has a reset button.

B) With the power shut off and the wires disconnected from the element, check the element for resistance using a volt Ohm meter. The correct resistance can be found in the owner’s manual. If no resistance is present, the element is bad and needs replacing.

Note: Make certain there is water in the water heater tank when operating on electric, as an un-submerged electric element will quickly burn up.

Here is a helpful video outlining the different components of RV water heaters, what they do, where they are located along with maintenance, and some additional RV water heater troubleshooting tips.

RV water heater trouble shooting can be easily and quickly performed with a little knowledge and basic tools. Hopefully the information you have learned will help you be more prepared.

Track your RV maintenance

Be sure to keep track of all your RV maintenance with an online tool such as RV LIFE Maintenance. Not only can you keep all your maintenance records and documents in one place, you’ll receive timely reminders via email when maintenance is due and potentially avoid a costly repair or serious accident.