How do I heat water in a van?

Your choices at a glance

Hot water in a van comes down to three pathways. Propane tankless units provide strong flow and quick recovery with careful venting and gas management. Diesel hydronic systems heat coolant that passes through a water heat exchanger and can also supply cabin heat. Electric heaters serve small tanks or short bursts on shore power, with careful battery math for off grid use. Each approach can deliver consistent water if you match fuel type and power needs to your travel style.

When to pick propane

Propane shines when you want on demand hot water with normal flow. A typical 40 thousand BTU per hour tankless unit can raise water by about 50 degrees at roughly 1 and a half gallons per minute. Use direct vent models rated for mobile use, install a proper pressure relief valve, and route combustion outside. Keep tanks secured, lines protected, and add a gas detector near the floor.

When to pick diesel hydronic

Hydronic heaters burn diesel to warm a closed coolant loop that feeds a plate heat exchanger for domestic water. The same unit can run an air heat exchanger for the cabin, which makes it attractive for cold weather travel. Output ranges near 5 to 17 kilowatts allow steady showers at reasonable flow with modest fuel burn. Choose altitude ready models and route exhaust and intake outside the living space.

When to pick electric

Electric can work if your expectations match your battery bank. Heating one gallon by 55 degrees uses about 134 watt hours. A quick sink wash might only need a half gallon, while showers use several gallons. Electric tank heaters in the 6 to 10 liter range are practical with large lithium packs or shore power. True electric tankless demands very high current and is not practical off grid for most vans.

Sizing and power math that actually helps

Start with the temperature rise you need. If your source is 50 degrees and you want 105 degrees at the tap, your rise is 55 degrees. At 1 and a half gallons per minute, that calls for roughly 37 thousand BTU per hour from a heater. If you run electric, multiply gallons by 134 watt hours for a 55 degree rise, then divide by system efficiency to estimate battery draw. A four gallon shower at 80 percent efficiency is roughly 670 watt hours consumed before inverter losses.

Flow rate and mixing

Flow rate drives comfort. Many van showers run between 1 and 1 and a half gallons per minute to conserve water and energy. A thermostatic mixing valve set near 120 degrees helps prevent scalds and stretches hot water by blending with cold. Low flow fixtures and pause valves improve control, but keep in mind that extremely low flow can cause some tankless units to cycle off.

Batteries, alternators, and inverters

For electric heating, check inverter surge and continuous ratings. A 120 volt, 1500 watt element draws about 125 amps from a 12 volt battery bank before losses. Alternator charging or a dedicated generator can help replenish large draws. Use proper wire size, fusing, and ventilation around power components to maintain safety and efficiency.

Fuel use and safety

Propane and diesel both need clean combustion and correct venting. Install a carbon monoxide detector and test it often. Inspect burners and exhaust paths on a schedule, and keep spare fuel filters handy for diesel systems. Store fuels in rated containers and secure them to survive rough roads.

Plumbing realities in a moving vehicle

Mobile plumbing lives a harder life than house plumbing. Vibration, temperature swings, and tight spaces demand tough materials. PEX with quality fittings, an accumulator for smoother pump operation, and a pressure relief valve near any tanked heater keep things stable. Insulate hot lines to reduce heat loss and consider a short loop to minimize the cold slug when you open the tap.

Layout that reduces waste

Place your heater close to high use fixtures to shorten the run. Use gentle bends and minimal fittings to cut flow loss. Add a drain down strategy at low points so you can winterize quickly without tools. Keep access panels for filters, valves, and electrical service points.

Water quality and filtration

Hard water can scale heat exchangers and elements. A simple inline sediment filter ahead of the pump protects components. If you camp in mineral heavy regions, consider a compact cartridge that targets scale. Descale tankless units per the manufacturer’s interval to maintain performance.

Maintenance that extends life

Set a schedule. Check hose clamps, inspect for chafe, test the pressure relief valve, and clean intake screens. Run diesel heaters periodically even in summer to keep fuel lines healthy. Log fuel use, service dates, and any changes in performance to spot issues before they strand you.

Comfort features that punch above their weight

• Thermostatic mixing: Stable temperatures at the tap with less scald risk
• Recirculation or bypass: Reduces cold slug and saves water when designed correctly
• Insulated tanks and lines: Retains heat and lowers recovery time
• Smart controls: Temperature and flow monitoring that prevent short cycling

Cold weather considerations

Freezing is the enemy. Insulate lines, add heat pads where appropriate, and route plumbing inside conditioned spaces when possible. Some hydronic systems can circulate warm coolant near vulnerable runs, which protects plumbing and keeps recovery times short on icy mornings. Always have a drain plan if you leave the rig idle in freezing temps.

Professional solutions that work on the road

If you want hot water that performs in real travel conditions, match the system to your power, your climate, and your space. Propane tankless delivers strong showers for families. Diesel hydronic pairs water and cabin heat for mountain seasons. Compact electric tanks serve light users or shore power stays. The right answer often blends components, like a hydronic loop feeding a plate exchanger and a small insulated reservoir controlled by a mixing valve.

OZK Customs designs and installs complete hot water systems inside full builds and partial upfits, integrating fuel storage, venting, and safe plumbing for dependable results. Explore our Recreational vans to see how water systems fit into entire layouts, or start a custom van build that aligns water heating, electrical, and climate into one plan. Looking to finance a preconfigured shell that can accept a refined water package, see our mainstream vans for platforms that book value and travel well.

What to expect with a pro install

• A clear assessment of power and fuel that suits your travel
• Venting and safety devices placed exactly where they should be
• Service access planned from the first bolt, not as an afterthought
• A handoff where you learn your system in plain language

Ready to make hot water a sure thing, not a guess? Share how you camp, your climate, and your crew size. We will spec the right heater, controls, and plumbing for your van and deliver a system that works all year.

Strong finish Want hot water without worry? Tap our team for a complete plan and install that ties water, power, and heat into one dependable package. Reach out and we will map your build from day one.