How do I keep my RV’s on-demand water heater from freezing?

By Dave Solberg
Dear Dave,
Grand Design installed a Furrion 2.4 gpm tankless water heater in the Reflection. I did some research on this heater, and the heater manual recommends not using it below 39 degrees F. Well, that is almost impossible in Oregon. My dealer was not aware of this. Bottomline is the heater froze and looks like it’s toast, per mobile repair tech. Question is, do you know if Furrion has done anything to address this issue? I’m probably due a new heater, and dealer has recommended apples to apples for replacement. Thanks. —Steve L., 2021 Reflection 303RLS

Dear Steve,
Since the water heater has an exterior vent and water in the system, it has the potential to freeze at temperatures below 32 degrees. That has been the issue with on-demand systems as they sit dormant until a faucet is opened and the call for water pressure.

Furrion has a new module board called Control Unit With Freeze Detector that is designed as an antifreeze option. It turns the unit on automatically if the temperature goes below 38 degrees and heats the water to keep it from freezing. It will then shut off at 58 degrees.

Furrion Anti-freeze protection

According to the Furrion website, the new models have the Anti-freeze Protection called Vortex + Anti-freeze Protection.

According to Furrion, unlike traditional limited-capacity tank systems, your hot water supply will not run out. The Vortex technology prevents cold spots by mixing the water prior to delivery, preventing inconsistent water temperatures. With the new anti-freeze protection feature, the RV tankless water heaters will deliver hot water during any camping season.

It does seem like a waste of propane to constantly cycle on and off during below-freezing temperatures. I did see several posts in forums that owners bought a shop light with a 40-watt bulb and placed it in the compartment. We did that in pop machines back in the early days and it worked well. But I’m not sure if I would want to “test” that with a new unit.

Truma on-demand water heater

Another option is the Truma model that has a 12-volt heater that turns on when the water gets close to freezing. That seems to be a better option than running the propane so often. I guess it all depends on if you are boondocking and what you have for 12-volt amp-hour capacity.

We did a video review at the Tampa SuperShow on the unit for RV Lifestyle and Repair Club. The unit has a quick-drain feature for winterizing that was very impressive. Just pull down the handle and it drains all the water. So you could manually winterize it if you know you will not be needing hot water for awhile. Otherwise, you could install a bypass valve and pull the drain plug on the other models.

 You might also enjoy this from Dave 

Can I install a single on-demand water heater for RV’s kitchen and bathroom?

Dear Dave, 
I purchased this trailer in November 2021 from Lazydays outside of Memphis. It was known I was taking the trailer to my home in Maine. The trailer was parked all winter in Maine. In the spring I took it to my lot in Northern Maine. Well, all the water lines were damaged, and the water heater didn’t work. Lazydays apparently hadn’t winterized the trailer, and I never asked them if they did. My question is, can I install a single on-demand water heater that would take care of the kitchen and bathroom? Usually, it is just me at the trailer, so I don’t use a lot of hot water. Your sage advice will be appreciated. if my solution isn’t feasible, any advice? —Bill, 2018 38-ft. Keystone Cougar fifth wheel MKS37

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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