ARTICLE: Water Heaters for RAM ProMaster Vans

Last updated: October 12, 2026

Hot Water in a Ram ProMaster: Picking the Right Heater

A good hot water setup is one of the upgrades you'll notice every day in a ProMaster: washing up after a long drive, cleaning greasy pans, warming your hands at the sink on a frosty morning. Settling on heater size, power, and location early keeps your options open and makes the rest of the build easier to lay out.

Pundmann models

Pundmann offers four configurations: 3L, 6L, 9L, and the 6L Tower. The Tower stands upright instead of lying flat, so it uses height instead of floor space. That suits the ProMaster's tall, nearly straight walls, and it's often the easiest fit in a 118" or 136" wheelbase, where every inch of floor counts.

All four run on AC and DC. On 12V, the element pulls around 200W. On shore power or an inverter, the 500W or 1000W AC element brings the tank up to temperature much faster. Use whichever power is available at the time.

Which size fits how you travel

  • 3L: Enough for dishes, washing up, and quick rinses. A good match for weekend rigs or a galley-only setup.

  • 6L / 6L Tower: Works for solo travelers, or for couples who shower every other day with a water-saving head.

  • 9L: For daily showers, two people, or running the sink and shower at once. The longer 159" and 159" EXT have the most room for it.

A larger tank stores more hot water, but it also takes longer to reheat once it's used up.

Battery impact

Heating a full 9L tank uses roughly 33Ah from a 12V lithium bank. Add a DC-DC charger off the alternator and you can heat on the move, so the water is hot when you park.

Finding a spot for it

A low cabinet or the space under the galley counter protects the heater and keeps its weight down low. The ProMaster's front-wheel-drive layout gives you a flat, low floor with no driveshaft tunnel, so low cabinets end up with plenty of usable depth. It's also the widest of the big three vans, which often leaves open space next to the wheel wells that the Tower fits well. Put the heater close to whichever fixture you use most, or halfway between the galley and shower if they're at opposite ends.

Plumbing

Put a thermostatic mixing valve between the heater outlet and your fixtures. It mixes in cold water to hold a steady, safe temperature, and it stretches your hot water supply further. [TK: confirm max inlet pressure and whether a pressure-reducing valve is recommended with typical van pumps.]

Winter use

In a ProMaster with good insulation, water heated the night before is usually still warm by morning, so the element only has to top it up. When you're storing the van or expecting a hard freeze, drain the heater first. Water that freezes in the tank expands and can crack it or damage the fittings. Draining takes about half an hour and costs far less than a replacement.