12V vs 110V Water Heaters: Which One Fits Your Build?

If you've started shopping for van water heaters, you've probably noticed most of them list both a 12V and a 110V (or 230V, if you're looking at European brands) option, sometimes both on the same unit. Here's what that actually means for your build.

Pundmann Therm 6L Tower dual voltage water heater
Dual-voltage units like this one let you switch between 12V and 110V depending on where you're parked.

12V Runs Off Your Battery Bank Directly

It's simple, doesn't need shore power or an inverter, and works anywhere you park. The tradeoff is heating speed: a 12V element (commonly 180–200W) heats water more slowly than an AC element, so it's better suited to smaller, more frequent top-ups than one big daily heat cycle.

110V (AC) Uses Shore Power or Your Inverter

These elements run much higher wattage, often 500W or more, so they heat water noticeably faster and recover quicker between uses. The catch is obvious: if you're not plugged into shore power, you're pulling that wattage through an inverter from your battery bank, which adds up fast on a full day of van life away from hookups.

Dual-Voltage Units Give You Both

Plugged in at a campground or driving with your inverter topped off? Use the 110V side for faster recovery. Boondocking and being careful with your battery bank? Switch to 12V and let it heat more slowly in the background. This flexibility is why dual-voltage compact boilers (Pundmann's lineup being one common example) have become popular for builds that split time between off-grid stays and hookups.

Which Should You Pick?

If your build is strictly off-grid, weekend-trip focused, or running a smaller battery bank, 12V-only keeps things simple and low-draw. If you're full-time, near shore power often, or running a larger inverter/lithium setup already, dual-voltage gives you the best of both without forcing a choice up front.

See the water heater lineup for the 12V, 110V, and dual-voltage options available.

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