Water Heater Backfire When Lighting: Causes and How To Fix

You may not have seen it, but it can happen. Water heaters can backfire even though they do not have an engine. This is always a possibility when you have gas-powered appliances. It is just not fun to watch or listen to as something is wrong with the appliance.

One cause can be a propane build-up somewhere in the ignition system of the water heater. When you go to light it, the built up gas explodes and it sounds like a backfire. Have a professional take a look if you are not up to the task.

To learn more about this problem, just continue to read our article. It has the information you need to know about so you can handle this problem if it happens to you. Take a few minutes to see how this important information helps you solve a problem.

Water Heater Backfire When Lighting

Just about no one is talking about this important problem. We say it is important because backfires are not always harmless. It is hard to diagnose the cause when you are not a professional that understands water heater systems completely.

The best that can be said is that there is a problem somewhere in your ignition system that is causing the propane to build up. Then when you go to light the water heater, the flame or the spark ignites the built up gas and causes a little explosion.

If you do not know how to fix your water heater, then it is best to call in a technician and let them handle any repairs. The cause may be due to a backdraft due to improper installation and venting.

It is hard to say and a thorough professional investigation may be the ticket to getting the problem solved.

What Causes a Water Heater To Backfire


Besides the one we just mentioned, there are about 2 others that we could find in our research.

1. There is a bad air to fuel mixture- too much fuel in the mixture can cause the gas to explode instead of just light. Sort of like pouring gas on a pile of sticks and waiting a moment before lighting the pile. The explosion is due to the build-up of gas and too little air in the small area.

2. A wide spark gap- this may happen on a DSI heater and depending on the brand name it may or may not be adjustable. This wide gap has been known to be the cause of the backfire.

To fix the former problem, you can adjust the damper but only if you own an Atwood water heater. The Suburban damper is not adjustable. For the latter problem, you should call in an expert and let them fix it.

They know the correct gap and will have the right tools to make the adjustment. Then let them show you how to make that adjustment so you can do it yourself if you are camping away from town.

It is hard to properly diagnose this problem simply for the fact that all ‘water heater complete guides’ do not touch on this subject. This may be because it is not a common occurrence with RV water heaters.

Also, some repair men have only seen this problem on furnaces and not water heaters. That would be another reason why no one is writing about this topic. When it happens to you, do not try lighting the propane water heater again until you get a professional to look at it.

Use the electrical side if you can so you have enough hot water for you and your loved ones. Then wait for the professional to arrive.

How To Fix Water Heater Backfire


Since no one is talking about this problem, the information regarding how to fix it is sparse. The first thing to do would be to check your gas supply. It is possible that too much gas is coming through the line and causing the build-up.

Try turning the gas flow down a little bit and see if this solves the problem. If the problem still occurs, then check the ignition system to see if it is operating correctly.

If not you may have to buy and replace parts to get it working again. Third, check the installation and vents to see if they are all properly installed. If not you may have to spend some time and money fixing this issue.

Finally, check the level of your RV or trailer. When it is not level gas can build up and cause this problem. Just re-level your RV or trailer and see if that solves the problem.

RV appliances need proper leveling for them to work right. That option should probably be checked first not last. The last resort would be to call in a professional.

Going Tankless


If this problem continues or can’t be repaired, you may want to consider installing a tankless water heater. These devices work far better than the old tank water heaters.

Plus, they do not run out of hot water. There are quite a few models to look at. Buying one may be cheaper than buying a new traditional RV water heater from Atwood or Suburban.

This change should also spare you the backfiring issue that some RVers experience. This seems to be a rare problem but it is one you should avoid if you can.

Some Final Words

In our research, we found only 1 location that mentions this problem. There were only 3 comments made with very little information given about what causes and solves this issue.

What we suggest, is that you talk to your RV mechanic, or qualified technicians even if this has not happened to you yet. It may happen and having the right information on hand before it happens allows you to fix the problem quickly. And before it gets worse.

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