How to Convert Your RV Water Heater to Tankless

convert RV water heater to a tankless heater

RVers’ lives are full of excitement and adventures for which they could use a nice shower after spending hours outdoors. With the limitations that standard heaters have, that enjoyment can really be badly interrupted.

In RV, every inch matters, and therefore most of RVs have water heaters for up to 6 gallons. Given the fact that these 6 gallons can be used up quickly, there is only one solution. Tankless RV water heaters!

Now, let’s see what the benefits are and how exactly you should do this and convert RV water heater to tankless.

Converting Your RV to a Tankless Water Heater

It’s quite simple. First, you need to remove the tank water heater unit, and then you install the tankless, right? Easier said than done. Let’s see what you really need to do here.

Removing the old water heater

First of all, there are some safety measures that you need to consider.

Turn your LP gas off. This is the first thing to do as you might face some unwanted problems otherwise.

Then, you want to get inside of your RV and make sure that your water pump is switched off. The one thing that you don’t want to see is water pumping out of your lines all over the place.

Afterward, double check to see where your DC power is supplied. Disconnect the wires from the fuse box (if it’s connected to the solar batteries, and it probably is). Well, whatever the source of power is, just cut it off. Not literary cut, but unplug it or something.

Check your main light in the living room to see if you’ve managed to cut the power supply successfully.

Once these safety measures are pleased, you are ready to start converting your RV water heater to tankless.

First of all, you need to make sure that the closing doors that lock your water heater are of proper size. Measure it carefully, and order the one that will fit perfectly. These doors are of high importance and they need to be waterproof and rustproof. You shouldn’t be putting your water heater in something susceptible to rust.

Once all the parts are ready, it’s time to remove the old water tank and put in some new RV tankless water heater.

To do so, you need to empty the old water tank completely. There is a pressure relief valve that you can use and there is a drain valve on the bottom side. You are going to need to relieve all the pressure out of this hot water tank by opening up the pressure relief valve.

Be prepared: the water will shoot out of there so you just need to stand out of the reach and let it do its thing.

Once all the pressure is out of the tank, you will need to get a socket wrench and get this drain valve unplugged so that you can let all the water out. That should drain the tank completely, and you will be ready for the next stage.

You need to get drain plug unscrewed with a crescent wrench. If you are dealing with the older RV, this might be problematic as there will be a vent standing in your way. On the other side, that vent should be easy to remove.

Unscrewing it should remove the water from the tank completely.

Furthermore, disconnect the gas line, the hot and the cold water lines, so that you can unscrew it and remove the whole unit.

Once all are disconnected, just unscrew all of the screws that are holding the unit. Use the putty knife and a hammer to loosen up all the butyl tape, the tar tape, and the caulking around so that you can remove the whole unit.

Before you start installing your new water heater, here’s a really useful video on how to!

How to Install Your Tankless RV Water Heater

Take your putty knife and go around and clean off all the edges while using mineral spirits as they will clean it much easier and better than anything else.

Use some gloves while doing this! Clean it all up and you are ready to start the installation.

Put in the new RV tankless water heater inside, and make sure that it is framed in tightly, so it doesn’t move around. You can probably use the so-called sticker wood to fix it up.

Next, before attaching the door to the unit, you need to layer a butyl tape on the outside edge so that when you screw the door to the siding there’s a nice watertight seal. Once you get that door screwed onto the siding, then you can attach the unit to the door.

Now to the technical part: the first thing that you need to do when reattaching the lines in the back is to put Teflon tape on both the hot and the cold water connections on the back of the RV tankless water heater. This will give you a lot more space and room to work with, as it will be much harder to put the Teflon tape on after the unit is installed.

Next thing is installing your hot and cold water lines.

All you need to do is cut the cold water line so that the attachment will fit nice and easily on the back of the hot water heater. To connect it, you can use SharkBite 3/8 inch straight coupling and it should seal all the gaps and create the watertight seal which will provide you with basically a straight pipe again.

Once the hot and cold water lines are installed, gently curve the copper LPG line so that it would attach cleanly on the back of the hot water. Use a crescent wrench to tighten it down, and it should fit perfectly.

Furthermore, you will need to do the wiring part. Remove the faceplate on the user control panel so that you can attach it near the water heater.

Once mounted, you can wire user control panel (2 wires) with the ones that were coming out of the back of the hot water heater. Usually (but not necessarily) user control panel wires would be colored in black, while the ones coming from the back of the hot water heater are blue.

If you have done all the previous steps successfully, the next thing is turning on the water pump in the LPG lines so that you can check to see if there are any leaks.

If none are found, reconnect the 12-volt power to the fuse box and the power on the unit and test it.

The unit should immediately engage whenever you turn on the hot water in the shower, or wherever you want.

The benefits of having a tankless water heater in your RV

1. They are compact

They definitely take a lot less of space than the ones with tanks. Given the RV life, every inch of your space is priceless. To someone who is living in 200 sq/ft apartment this might seem irrelevant, but to those in RV, every inch matters.

2. Economical

It’s a well-known fact that tankless RV water heaters consume as less as up to 50% of energy in comparison to the regular water heaters with tanks. Whether they run on electricity or fuel, it’s quite a difference that they make!

3. No water waste

When in RV, you have a limited water supply. Every drop of water is precious. Therefore, tankless RV water heater heats the water almost instantly, and you won’t need to wait for the cold water to pass until hot water reaches you. Everything is instant, and hence, this affects your water savings.

4. Great longevity

On average, tankless RV water heaters can last up to 2x longer than the regular water heaters. A rough estimation is around 18-20 years in comparison to 8-12 years of what you can get with the regular water heater with a tank. Besides, they have parts that are easier to maintain, or even repair if there’s a need to.

5. Unlimited hot water stream

Needless to say, this surely is one of the benefits that make you go with the tankless RV water heater in the first place. No more worries about the water heater tank size!

6. More convenient

You won’t be facing some unpleasant issues as you might face with your old water heater- no leakage, for example. They can be installed in a smaller space mounted wall, as well. The water will be fresh, directly coming from the source, instead of from the tank where it can stay for days (and lose its freshness).

Here’s an awesome video from Jared & Kris of the YouTube channel All About RV’s on the advantages and disadvantages of going tankless or not!


Overall, it’s not that hard to install a tankless RV water heater. There will be more problems in preparing everything – removing the old one and cleaning the space for the new RV tankless water heater.

Anyway, with RV, you never know where the road is going to take you and how long will you be off. Therefore, having these “little home comforts” of never ending hot water and such are just the thing that can make the trip much more interesting.

Hopefully, this article helped you convert old RV water heater into something that saves a lot of space and provides endless streams of hot water.

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