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Ask Dave: Why won’t the water heater heat water?

Answers to questions about RV Repair and Maintenance from RV expert Dave Solberg, author of the “RV Handbook” and the managing editor of the RV Repair Club. This column appears Monday through Saturday in the RV Travel and RV Daily Tips newsletters. (Sign up for an email reminder for each new issue if you do not already receive one.) Today Dave discusses a water heater that won’t heat water.

Dear Dave,
I went camping a week ago and the water heater fired up properly. Ten days later, in another campground, the water heater failed to produce heat. The heater portion would start up and then stop without firing up the propane. I repeated the process many times, to no avail. At the same time I tested all other propane appliances; they were all working as normal. The batteries were hooked up to a trickle charger at the campground power. If relevant, I am in a 1997 34-foot Airstream. What could be the problem? —Paul

Dear Paul,
The first thing I would check is to see if the gas valve opens. It should have a “click,” then an attempt to spark from the ceramic igniter. If the ceramic has a crack, the spark will follow the crack to ground and not to the burner assembly. Also, the spark probe could be bent or even broken off due to rust and throwing the spark to another part of the assembly.

Is the burner in the water heater not staying lit?

Next, is the burner actually lighting but not staying lit? If so, there is a thermal coupler just above the burner which creates a closed circuit when the flame is burning as it touches it and tells the module board there is flame, so to keep the gas valve open. It the flame does not touch this probe, it creates an open circuit. Then the board thinks there is no flame and will shut the valve rather than fill the rig with propane. This coupler could also be defective.

If you hear the gas valve click open and the spark igniter trying to light, check the burner tube to make sure there are no obstructions. Spiders love the smell of propane and can spin a web that will block the flow of propane inside the burner tube.

Check your house battery charge

I sound like a broken record every time I give advice on an intermittent appliance issue and say “check your house battery voltage.” If you have lead acid batteries, sulfur coats the plates as the charge is drained down. If you do not have a multi-stage charger that produces 14.4 volts in the initial bulk or conditioning charge, it will not break up the sulfation and it will get thicker with each cycle until it will not hold a charge. It’s deceiving, as the voltage looks to be fully charged at 12.6 volts. But, as I’ve mentioned before, it’s like a bucket full of water with a hole in the bottom. As soon as a load is applied, the voltage plummets and is not enough to run the appliance.

Even if you are plugged into 120-volt power, there might not be enough charge power coming from your converter to sustain the power needed to run the water heater. Try connecting a battery booster that puts out more than your trickle charger to see if that helps. I’m not sure why the other appliances work. However, I have seen stranger things happen in RVs when it comes to 12-volt power.

Read more from Dave here

Dave Solberg worked at Winnebago for 15 years developing the dealer training program, as marketing manager, and conducting shows. As the owner of Passport Media Creations, Dave has developed several RV dealer training programs, the RV Safety Training program for The Recreation Vehicle Safety and Education Foundation, and the accredited RV Driving Safety program being conducted at rallies and shows around the country. Dave is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.

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