What to Do When Your RV Hot Water Heater Won’t Light

Being an RV owner can be great. You have your own private space to take a shower when camping. Of course, hot water would help the situation.

The first way of realizing your RV hot water heater won’t heat often involves washing the dishes or stepping into the shower. The cold water won’t go away! The next step is troubleshooting where your hot water went and why it’s not working.

RV hot water heaters can readily have hardware issues that prevent them from working, including bad circuit boards and thermocouplers, or even a defective ignited. Thankfully, all are fixable. Let’s explore potential problems.

Starting with the obvious: propane and water

An RV hot water heater needs two main things to get started: Propane and water. Run out of either of these and the water heater won’t do much.

The first thing to do is make sure you have a supply of propane available for the hot water heater. If the tanks feel light or the gauges indicate they are empty, you’ll need more propane to use any heat in your RV, including your furnace.

You can see how much water is left in your fresh water tank via gauges on the dashboard. Opening your hot water heater’s pressure relief valve will also show you if you have water in the hot water heater.

Technical issues: Your thermocoupler isn’t working

The thermocouple is among the small parts that help your water heater know when to work. Unfortunately, this also means that a bad thermocouple can stop your water heater from working.

The thermocoupler is found within the pilot light. The pilot light could be on but a non working thermocouple tends the whole heater that nothing is happening.

The thermocouple can also be covered in soot and dirt. The easiest, safest way to clean the relatively sensitive thermocouple is to use compressed air. You won’t have to reach too far and the force of the air is more gentle than using what some people use, like drill bits – which can make the opening too big.

Pilot burner problems

The pilot burner itself can be clogged. Again, compressed air is an excellent option to blow out soon. You can also remove any part of the pilot light possible.

These parents are often just screwed in and fed natural gas, so having the flow of natural gas through them is essential to having your water heater run.

For both your thermocouple and the pilot burner, soot and debris can be a problem in RVs, especially in dusty and dirt filled areas. You might not intend to track in dust and dirt – but it’s easily possible for debris to make it’s way into your hot water heater.

Insects can also be a problem. Spiders and insects like the smell of propane and the warmth, so they tent to try to crawl into pipes. Dead spiders in abundance can create a clog within your natural gas line.

Direct Spark Ignition Problems

Direct Spark igniter hot water heaters are becoming more common in RVs. DSI hot water heaters are simple and allow the user to flip a switch to turn the hot water heater on. 

A DSI system doesn’t have a pilot light, which is normally used to initiate the spark. A 12V battery produces the spark instead.

Board Problems

The most common problem with a direct spark ignite system is a bad board or a bad fuse. A bad fuse can be a small break in the chain that tells the spark to start. 

A bad board results in the electronics being able to know when to fire. The control board often has lights to communicate when an issue is happening. Your best bet is to grab your manual or use the internet to learn what the board is trying to tell you.

In some cases, the board needs to be replaced. Some DIYers can replace boards themselves.

No Ignition for Direct Spark

The gas valve might be stuck if you don’t have a board issue. In this case, you might want to tap the gas valve lightly to see if anything is obstructing it, as the most common issue here is that the gas isn’t getting through.


Make sure your battery for the 12V and plug in are working. Power might have been cut off for some reason. Look at the circuit box to make sure that your hot water heater breaker isn’t off.

Fewer Moving Parts

One of the advantages to a DSI system is that there are fewer moving parts and a constant flow of propane isn’t needed to power a pilot light. The bad side to a DSI system is that most parts are electronic and simply cleaning out parts will help less often. This could also be good because DSI systems are less affected by dirt and soot.

Do you smell gas?

Both DSI and regular hot water heaters use propane gas to ignite a flame to heat water. If the lines aren’t obstructed,  and everything else is working, you might actually have a leak.

Propane companies are required to add a rotten egg scent to their gasses so you can readily detect the nasty odor.

If you smell something, it’s probably not an issue within the hot water heater. You have a leak. 

Propane is invisible and explosive. Turn off the supply of propane right away, both inside and outside, and let your RV air out. Open windows and doors. You can find the source of the leak later – just ensure you are safe at the moment.

Don’t try to repair gas lines yourself unless you have plenty of experience or work within the field. Working with gas lines can be dangerous and explosive.


Hot water heaters can be a bit fickle. Cleaning out a pilot light based hot water heater can readily take care of some issues. Additional parts and help might be needed. A DSI hot water heater can often communicate it’s own issues to you via blinking lights on the board, which is an excellent head start.

We hope you get to experience hot water again very soon.