Camper Van Water Heater

Hot Water From Your Diesel Heater!

During Lockdown, I was looking for a way to get enough hot water for us all to have showers. A sort of camper van water heater. All the campsites were open but only to self-contained units that had their own facilities.

I came up with an idea of how to heat the water from our cheap Chinese diesel heater. While looking for the parts to build it, I discovered a company that had designed and sold their version of what I had invented! It just goes to show that no idea is original. There are probably hundreds of people who had thought of the same idea.

The company in question wanted £250 – £700 for a kit. My version costs around £80! I think it’s important to add that my version looks nowhere near as pretty but it’s just as functional.

How Does it Work?

it’s quite simple really. 2 heat exchangers sit in front of the hot air being blown from your diesel heater. While sitting there, water is pumped from a tank through the heat exchangers and back to the tank. An optional temperature controller allows you to set the temperature. This controller only stops the pump, it doesn’t stop the diesel heater. Here’s an illustration to help you understand.

What is needed to build it?

Here’s a list of all the parts for the camper van water heater. I won’t include the parts for the shower and shower tent until later on in the article.

24 litre water box click here
Hot air diverter Click here for eBay version
2 x heat exchangers click h e re
Submersible water pump 12v click here
Temperature controller (optional) click here
silicone tube click here
Aluminium heatproof tape click here
A diesel heater if you don’t have one click here

If you choose to purchase these items, make sure the sizes all match up with each other including your diesel heater hot air pipe. There are many size options so make sure you choose the correct one to match.

How Do I Assemble the Camper Van Water Heater?

Firstly cut your hot air duct and place the hot air diverter in a convenient position. Try to keep the distances short to your chosen location of the water tank. This will help to prevent heat loss with the water in the pipes and will also cost you less for pipes and equipment.

Next take your two heat exchangers and bind them together along the edges with the aluminium tape.

Bind the heat exchangers to the hot air diverter with aluminium tape.

Each heat exchanger has two connections. Use a short loop of silicone pipe to join two heat exchangers, then cut the remaining piece of silicone hose into two and link them both to the heat exchangers. You will have something like this..

pipe from pump—heat exchanger—heat exchanger—pipe back to water tank

Here’s what it looks like in my van

connect the 12v water pump to the end of one of the silicone hoses coming from the heat exchanger.

put both hoses, one bare hose and one with the pump, inside the water tank. I cut a hole in the top of my water tank so I could easily remove the pump and replace with the shower pump

water pump going through hole in the top of the tank

If you have chosen to fit a temperature controller, wire this to a 12v connection and the switch side of the controller to the water pump. This allows you to set a temperature and the pump will stop pumping when the temperature is reached.

Test The System

The air diverter you have purchased allows you to direct the air through the heat exchangers rather than it’s usual path. Fill the water tank with 24 litres of water. Start the diesel heater, divert the air to the heat exchangers. Place your pump and return pipe in the tank. power up the controller with 12v and sit back and watch the temperature climb.

As you can see, my temperature controller is set to 47 degrees Celsius. This is way too hot for a shower, but once you have reached temperature, removed the pipes and water pump, carried the water tank into the shower tent, placed the shower pump in it, got your towel ready, and got undressed. Your temperature has just hit about 40 degrees so is perfect.

What you have is a camper van water heater that heats enough water for 2 adults and 2 children to have a short shower including hair washing in less that 35 minutes!

OLPRO do a nice shower/toilet tent here (a few peg holes in the bottom will allow for drainage.) and the rechargeable shower pump I use is here

Happy showering clean campers! feel free to ask any questions in the comments below.

next, check out how I fitted my solar panel and system, click here