campervan hot water heater

MY $300 DIY 12-VOLT CAMPERVAN HOT WATER HEATER

UPDATED 2021

Deciding on whether to have a hot water system in your van can be a tough decision.  It can add significant cost and complexity.

I settled on a bit more of a DIY version that costs less and for the past 6 years has worked great.  Let’s have a look at the most popular hot water systems and why mine is a great option if you don’t have deep pockets.

DOES YOUR CAMPER VAN NEED HOT WATER?

I know you want it but do you really need it.  Obviously a very personal choice here.  

We opted to go with hot water because we are full-time and having a hot shower was a must. If we lived down South and didn’t chase snow for skiing, hot water might have not been such a priority.  But for us we absolutely love it!

CAMPERVAN HOT WATER HEATER OPTIONS

Let’s have a quick look and get familiar with the different ways you can live the good life with hot water in your van.

COOLANT HEAT EXCHANGE SYSTEMS

In my opinion, this is the top dog in a campervan hot water heater.  These work by having a water tank that is heated by coolant that circulates through it.

While driving the coolant from the engine heats it or you can heat it via a diesel/petrol fired coolant heater.

This system even allows you to preheat your engine block which is a great feature for the cold.

Isotherm campervan hot water heater


IsoTherm
 is just one option but a very reputable one that has a long following in the sailing and yachting circle.  Just the tank will run you about $750.

To heat via coolant lines you’ll need to tie into the engines coolant system which is no small task.  For us the cost was too great and a bit complex for the DIY’er.

DIESEL OR PETROL FIRED HOT WATER SYSTEMS

webasto dualtop hot water heater

The Webasto Dual Top is another great option and avoids the complexity of tying into your engine’s coolant system.  The Dual Top also provides forced air heating in addition to hot water.

These are diesel/petrol fired and has an internal 11 liter hot water tank.  These can even be mounted outside of the living area underneath your van.  They have built in freezing protection features as well.  Not cheap though at about $3,500.

PROPANE ON DEMAND HOT WATER SYSTEMS

on demand propane hot water


These are becoming a popular option for those that are using propane.  These on-demand hot water systems can be hooked up to a propane tank and work great for outdoor showers.

You’ll see people with these hanging on their back doors.  They are not designed to be used inside because they require ventilation.  They are however very affordable at around $200.

rv hot water heater

Here you have the traditional RV propane hot water heater.  These require a large hole cut in the side of your van and in my opinion are a pretty dated way of going about hot water.  There are far better options in my opinion.

OUR DIY BUDGET 12 VOLT VAN HOT WATER SYSTEM 

We opted for a 12 volt system that heats while driving, solar power or on shore power.  This avoided the complexity and cost of a coolant heated version.

You can run it off batteries sparingly but it does draw quite a bit of power.  The version we built uses about 35 amps while the element is going.  The element of course turns off once up to temperature.

diy hot water heater for van

We used a residential Reliance 6 gallon hot water heater.  They now have a 2.5 gallon version that might be a good option for folks.

These are of course designed to run off 120v which we wanted to avoid so we swapped the heating element to a 12v element.

diy 12 volt heating element


The 12 volt heating element that we ended up going with was the 400 watt from Missouri Wind and Solar.  READ THE UPDATE BELOW WITH OUR NEW RECOMMENDATION

The Missouri Wind element comes in 3 different wattages.

  • 200 watts drawing about 16 amps
  • 400 watts at 35 amps
  • 600 watts drawing about 50 amps(NOT recommended)

***UPDATE 2021***

12 volt heating element for campervan

While we have never had any problems using the 400 watt heating element that draws around 35 amps, some have reported that the their thermostat stopped working after a while.  This is likely due to the 35 amps of current which is more than what the thermostat on the 120v model is designed for.

Going with the 200 or 300 watt element should solve this issue.


HEATING ELEMENT SWAP

Swapping the element is easy and no different than any other hot water heater.  Here’s a video showing how if you’re not familiar with it.

12 VOLT WIRING DIAGRAM

DIY campervan water heater wiring diagram

PARTS LIST

HOW HAS OUR SYSTEM WORKED?

We’ve been running this setup for over 6 years and it has worked flawlessly.  Absolutely no issues.

Once the water heats up it stays relatively hot for a good 16 hours.  At least warm enough to do some dishes.  When we take showers we try to do that after it’s been on for a while.

We typically don’t stay parked for days at a time without driving to trailheads and such so we never have a problem warming it up.  And when on shore power you of course are golden.

We use it a lot in winter and is easy to drain to prevent freezing.  We just ran a drain pipe through the floor.

IMPORTANT THINGS TO CONSIDER WITH THIS DIY HOT WATER SYSTEM

In our Ford Transit we have a heavy duty alternator so I’m confident we have enough spare amps to run the hot water heater as well as charge our battery bank while driving.

It’s important to know what your alternator is putting out because this could be a big drain and cause premature alternator failure.

It’s also important to never turn on the heating element without water in the tank. It will ruin the element.

We have an illuminated switch for the heater above the sink but I was afraid we might accidentally turn it on without realizing it.  So I installed a second inline switch that kills power to the whole system that I turn off whenever I drain the tank.

This assures that even if someone turns the switch above the sink on there will be no power going to the hot water heater.

FINAL THOUGHTS

Like i mentioned earlier, we’ve been running this system for 6 years now without a single hiccup.  It works great on shore power, battery(sparingly), and of course while driving.  

Because the tank is round it does make it a little awkward and not very space efficient.  I really like the IsoTemps mentioned above because they offer a square version. 

But for a hot water system that works great and can be done for well under $300 I’m very happy with it.

I hope you found this article useful and please don’t hesitate to ask questions.

Don’t forget to follow our adventures on Instagram @outsidenomad and be sure to share this on your favorite social media so you can reference it again later.

2 thoughts on “MY $300 DIY 12-VOLT CAMPERVAN HOT WATER HEATER”

  1. I’m planning to install a 12v heating element in a plastic water tank. I want to keep the element from bouncing and loosening or touching the bottom of the tank. What would you put between the element and the tank to keep the element stable?

    1. I’m not sure I understand. How big of a tank? When you say “between the element and the tank” where exactly do you mean? My initial gut feeling on this one is that it’s a really bad idea. Are you planning for a blow off system if it becomes over pressured?

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