RV’s hot water lines aren’t working. Could water heater tank be frozen?

Dear Dave,
During a winter storm in Alabama, the hot water stopped flowing in my motorhome. I assume the hot water tank is frozen. I assume the water heater needs to be turned off since I assume no water flows in tank. Forums are vague on this issue. I turned it off, as I didn’t want to start a fire. —Vicky, 2024 Jayco Precept 31UL

Dear Vicky,
First, let me congratulate you on the proper description of the water heater and tank. When I was at Winnebago Industries, the head of technical service drilled into me that there is no such thing as a “hot water heater”! He stated that if the water was hot, it would not need to be heated; so it technically is a water heater. However, within a water heater, there is a water tank. Since that is storing hot water, it can be called a hot water tank! He also had an issue with the word “irregardless,” which he stated meant “without without regard” (i.e., a double negative), which thus actually meant “with regard.” He was quite unique!

I doubt the water heater tank is frozen as it normally is enclosed in a cabinet and has some heat coming from the on-board heater. Plus, it should be still lighting the flame or using the electric heat element to heat the tank. I assume you have enough battery power and propane to run the furnace and water heater, or are plugged into shoreline power to run it on 120-volt power, if so equipped?

I would suggest finding the location and checking the tank. You should be able to do this by identifying the outside panel and then locating it inside the rig.

My guess is you have a hot water line that is running under a cabinet or that is not getting air circulation and heat, and the pipe is frozen. Try other hot water faucets like the shower or bath sink. Open cabinets underneath any sink and see if that helps.

Your rig most likely has PEX water lines, and they are very forgiving when frozen. I have found they expand to 1.5 times normal size without bursting. I have tested that in –20° weather in Fargo, ND. So, if you do have a frozen water line, hopefully it doesn’t cause damage. However, it depends on the connection fittings, as well.

If you do have a frozen water heater tank, that is not a good situation. The expansion of the frozen water most likely will split the tank. So, it is important to identify which component is at risk and get it addressed immediately. A split tank will cause the water to flow when it thaws and could cause some real damage that you will not see immediately due to the unit being enclosed.

Installing a heat lamp or heating pad in this area would help reduce the potential for freezing.

Here is an update from Vicky

Thank you for the information.

I believe in my case the water line to the water heater tank must have frozen. The following day I opened the door to the unit and the sunshine helped. I checked the water flow by releasing the pressure valve. Finally, the water was flowing. Fortunately, there were no leaks caused by this historic winter storm that came through the Gulf Coast.

I also used a 50-watt ceramic bulb in the wet bay during the cold spell. I believe that helped to keep the water flowing to the rest of the RV. —Vicky

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Dear Dave,
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Read Dave’s answer.

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Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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