Friday, March 24, 2023


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

Dear Bill,
When it comes to winterizing, I always recommend checking the low point drains, water heater, and ice maker if there is one in the refrigerator rather than leaving it to a dealer or service center. I have heard too many horror stories about water heater tanks freezing and splitting, water lines bursting, and pipes splitting.

Before putting in a completely new water heater, check to verify the tank has not split and then let’s troubleshoot why it is not working. I could not find a specific MKS37. However, there were several models that were 38’ long with the MKS designation. They all showed to have an electric/propane water heater, so I assume you have a 10-gallon version of that.

First need to fix damaged water pipes

Before you start troubleshooting or even swapping out the old water heater you will need to fix the water pipes that are damaged. Typically Keystone used PEX lines with crimp connections, so you might be able to replace a few as PEX does have the ability to expand about 1.5 times its original size. I have frozen a unit solid during an annual music festival we have here every February. When it thawed, I only had some minor cracks on the screen of the water pump and a few fixtures. You can get the PEX, splice connections, crimps, and crimp tool at any home improvement store, or get the crimps and tool on Amazon here.

Once you get the lines fixed, connect a hose to the city water fill or put some water in the tank and verify the lines are good, the water heater is not leaking, and the water pump is working properly. Plug the unit into a 120-volt source or make sure the house batteries are fully charged and open the propane tanks.

We just ran an article about one of our readers that had a similar unit and it was not working on 120-volt but did work on propane. He eventually found the heating element was burned out, most likely from running the unit on 120-volt power without water in the tank. You can read more on that here.

Make sure there is water in the tank

Make sure there is water in the tank. Since you said it doesn’t work, I would verify if it works on the LP mode or 120-volt mode to isolate what source is or is not working. If both are not working, check the circuit breaker on the distribution panel and the switch on the water heater for the 120-volt mode. Then check the automotive fuse on the distribution panel, as this will provide 12-volt power for both operations. You can verify 120-volt power and 12-volt power at the water heater with a multimeter. It may be as simple as a fuse or circuit breaker.

So, let’s address your original thought of replacing the old unit with an on-demand system. You indicated that you would like to install a single system that would only take care of the kitchen and bathroom. I would not recommend anything that is powered by 120-volt power as you will have issues if there is only a 30-amp service, and if you do any dry camping it will not work. Plus, most smaller under-the-sink models will not provide enough flow or capacity for much more than slowly filling a coffee cup for tea!

Several units available

There are several units available that run on propane and will fit in the existing cavity that your current water heater is in. Girard has been a popular model for many years and recently we have seen Fogatti, RecPro, and my favorite, Lippert. Truma also has one that we did a feature on at the Tampa Super Show; however, it can only be purchased at a dealership. The others are available through distributors like and Amazon, and the Furrion model can be purchased directly from Lippert online in their store at

Since you already have water, propane, and power in the existing cavity, it is a pretty smooth swap. The reviews are all very good and the swap-out video looks pretty easy. I have not done one myself yet, but hope to do one the next time we shoot content. has a good video on the removal and installation. However, I caution against a do-it-yourself job since there is electrical and gas involved, so it’s best left to someone qualified.

 You might also enjoy this from Dave 

My RV’s water heater has problems. Is it still usable?

Dear Dave,
I purchased a 2008 SnowRiver camper in August. When I winterized the camper I discovered that the anode had never been changed and was bare wire, with a lot of white sediment at the bottom of the tank. I used a spray wand to flush the tank and at that time I noticed a lot of black flaky paint (porcelain?) washing out of the tank. I looked inside the tank with a camera and saw places that were white where the black had flaked off. How do I know whether my water heater is still usable? I have heard that the concern with an unchanged anode is rust in the tank, but I could not see inside well enough to know whether there was any rust. —Toni

Read Dave’s answer.

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

Read more from Dave here


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Bill Braniff
7 days ago

Thanks Dave for the water heater info. My trailer is parked on my land. o running water I fill tanks from water brought from home. I have a 1200W solar system and a back up 4500W generator. Appreciate your speedy response.

Joseph Phebus
6 days ago
Reply to  Bill Braniff

If you do go the on demand route, you’ll use more water waiting for the water to get hot. It takes time in those units to fire up the heating element.

Just a thought if off-grid.

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