Water Heater Failure
December 28, 2012
Filed under Trailer Q&A
Q: We have a 2009 Fleetwood Formula toy hauler with a 10-gallon Atwood gas-only water heater. Last year during a trip we noticed water coming out on the floor from the water heater area and found the water heater dripping from the bottom, not the fittings. This messed up our trip due to keeping the water heater isolated until we really needed hot water and then we used rags and pans to catch the leaking water. After a little haggling Atwood did replace the heater. They inspected it and determined it was not a freeze crack but a rupture.
About the seventh week of using the new water heater this year I found water on the floor by the door of the cabinet where it is located. I removed the access panel and saw water dripping from the bottom of the heater. We are dry camping and using the water out of the trailer’s freshwater tank. I had just finished my shower when I noticed the dripping. I kept an eye on the drip until the water heater got to temperature and shut off. After about five minutes the dripping stopped. The air temperature outside went down to 40 degrees last night so my potable water most likely got close to that. Do you think the water heater, even though it has a foam insulation wrap, was sweating due to the cold water going into the hot tank? The first water heater never quit leaking when water pressure was on it.
J. Pauley, via email
A: This is an odd one. Many water heater leaks happen at the natural locations for leaks, which are the fittings and their attachment points. The tank leak with your old heater, caused by a rupture, is rare; most such failures are due to freeze damage. That’s why your Atwood tech checked that as a possibility.
You didn’t say where you live or how you store your trailer when not in use (Readers: It’s important to give us as much information as you can when sending letters to RV Clinic. The more data we have, the better we can help suggest a solution to your problem.) so we can not address climate concerns as part of the cause.
Cold water entering a hot tank is the same thing that happens with every other water heater and it doesn’t cause trouble with other users so I would rule that out as a cause. If you were on city water and didn’t use a regulator in the feed line, excess pressure could also have been a partial cause, but that would likely burst water lines well before the steel tank would rupture. Your leaks occurred when dry camping, so that rules out the city water pressure concern.
That you’ve experienced the same kind of trouble with two consecutive tanks is doubly unusual. The chance that you received two water heaters with the same unusual defect seems highly unlikely so we need to look at other factors with your situation. Our best guess on this is excess water temperature that would cause too much pressure inside the tank. Atwood recommends the temperature control be set at a midpoint between the lowest and highest settings. If you adjusted the control up from there, the hotter water could be the culprit. Check the adjustment, per your owners’ manual, lower the temperature and see if the leaking stops. You said, “After about five minutes the dripping stopped” and that could be when the temperature lowered a bit and/or some pressure bled off through the rest of the plumbing system. A once-over by your service tech may be the next step you follow beyond the temperature check.
— Jeff Johnston