Choosing the Right Water Heater: Type, Size & Power Source

Picking a water heater is really two decisions stacked on top of each other: what type of system fits your power setup, and what size actually matches how you use water. Get either one wrong and you'll either be babying your battery bank or hauling around capacity you never use.

Pundmann Therm 6L water heater
Pundmann Therm 6L, a common middle-ground size for van builds.

Start With Your Power Source, Not the Water Heater

If you're running a modest lithium setup (200–400Ah) with limited solar, a 12V-only unit with a 180–200W element is going to be a much better match than something pulling 750–1200W, which will hammer your battery bank if you're not plugged into shore power. If you've got a beefier electrical system or plan to be hooked up to campgrounds often, a dual 12V/110V unit gives you flexibility without forcing a tradeoff.

Then Think About How You'll Actually Use Hot Water

Quick dish-washing and the occasional rinse-off? A 3–6 liter tank is plenty. Daily showers for two people? You'll want either more volume, a faster-recovery unit, or a system that pairs with your existing engine or cabin heat so you're not solely reliant on stored capacity.

Don't Ignore Installation Complexity

Propane tankless units need to vent outside and involve gas lines. Great for endless hot water, but more complex to install safely. Engine-coolant systems need you to tap into your van's heater core, a bigger job than wiring in an electric boiler. Electric storage boilers are usually the simplest entry point for a first-time builder: no combustion, no exhaust, no cutting into coolant lines.

See the Pundmann water heater lineup for current sizes, voltages, and pricing.

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