Van Water Heating Systems

Why Does Hot Water Matter in a Van?

A hot shower is one of the great comforts of van life. Without it, you're showering in cold water, heating water on a camp stove (inefficient and limited), or finding a gym to shower at. A proper hot water system means you can wake up, take a real shower, and feel human.

Hot water also matters for dishwashing and hand washing. Cold water and soap don't mix well. A reliable water heater isn't a luxury — it's a quality-of-life essential.

What Size Water Heater Do You Need for a Van?

The right heater depends on how many people are in the van and how much hot water you want available. A solo traveler might be happy with a small heater that produces hot water for one quick shower. A couple or family needs enough hot water for two showers back-to-back.

Water Heater Capacity

Capacity is usually measured in gallons for tank heaters (10-20 gallons typical) or in output (liters per minute for tankless). A 15-gallon tank heater can supply about one full shower (10-15 gallons at comfortable temperature). A 20-gallon heater gives you two showers. For a couple, 20 gallons minimum.

Tankless heaters are sized by flow rate. A flow rate of 2-3 gallons per minute (GPM) at desired temperature is comfortable for showering. Lower flow feels like a trickle.

How Do Tank Water Heaters Work in a Van?

Tank heaters store and heat a fixed volume of water, maintaining it at temperature until you use it. They're simple, reliable, and widely available in RV sizes.

How Tank Heaters Work

Water sits in an insulated tank. A heating element (propane burner or electric element) heats the water to 120-130°F. The tank holds that heat, so when you turn on the shower, hot water is available immediately. Once the tank is depleted, you wait for it to reheat.

For vans, a typical tank heater is 10-20 gallons. Installation is straightforward: fresh water in, heated water out. The heating element is powered by propane (most common) or 120V AC electricity.

Propane Tank Heaters

Propane heaters are common in RVs and vans. They run off the van's propane tank, heat water fast, and work anywhere — campground or boondocking. Downsides: they produce heat constantly (even when you don't need hot water), which wastes propane. They require ventilation if indoors. They're slower to heat than instant options.

Electric Tank Heaters

Electric heaters run on 120V shore power. Useful if you're staying at campgrounds most of the time but useless when boondocking (unless you have a massive inverter running constantly, which wastes battery power). They're cheaper to buy upfront but are limited by power availability.

How Do Tankless Water Heaters Work in a Van?

Tankless heaters heat water on-demand. Water flows through a heating element, gets heated, and comes out hot. No storage, no waiting for a tank to heat up. They're efficient because they only use energy when you're actually using hot water.

Propane Tankless Heaters

Propane tankless models (like Girard brands) are common in RVs. Water flows through them, a propane burner heats it instantly, and you get hot water on demand. Advantages: compact, efficient, work anywhere. Disadvantages: smaller than you'd expect, they have a minimum flow threshold (if water flow is too low, they won't ignite), and they require ventilation. Most vans have enough flow for them to work fine.

Electric Tankless Heaters

Electric tankless heaters need significant power — usually 30-50 amps. In a van with a small inverter, this is impossible. They're not practical for mobile van conversions unless you're plugged into shore power constantly, which defeats the purpose of mobile living.

Advantages and Disadvantages

Tankless heaters are more efficient and take up less space than tank heaters. The downside is they have a delay before hot water reaches the shower (a second or two while water in the line heats up). For some people this is annoying. They're also slightly more complex and can develop mineral deposits if water quality is poor.

What Is a Truma Combi and Why Do Van Builders Use It?

The gold standard for van conversions is the Truma Combi — an all-in-one unit that heats your van interior AND provides hot water. This is what most ECB builds use.

How Truma Combi Works

The Combi is essentially two systems in one: a heating furnace for interior climate control and a water heater that uses the same propane burner. It efficiently manages both. The same propane flame that heats your van also heats water for shower.

It has a small internal tank (varies by model, usually 5-10 gallons equivalent) and produces hot water on demand. You control it from a digital panel inside the van — set desired water temperature and interior temperature, and it manages everything. Some models can run on shore power (electric element for water heating), propane, or both.

Why Truma Combi for Vans

The Combi is efficient (one burner for heating and hot water), compact (all-in-one unit), and reliable (Truma is the RV standard). It works on propane alone if you're boondocking, or switches to electric heating if you're plugged into shore power. It's the most practical choice for vans that need both heating and hot water.

The downside is upfront cost (higher than separate systems) and complexity (it does more, so more can go wrong, though in practice Truma units are rock solid). If you're boondocking in winter and need to stay warm, the Combi's dual function is invaluable.

Truma Models for Vans

Truma makes several Combi models. The most common for vans are the Combi 4 and Combi 6 (numbers indicate heating capacity in kilowatts). A Combi 4 is sufficient for most van conversions. It heats the interior quickly and produces adequate hot water. Larger vans or extreme cold might want a Combi 6, but most people don't need it. For builds that need hot water but not interior heating (warm climates, summer-only use), the Truma AquaGo is a compact tankless option that delivers instant hot water on demand.

Can You Use Diesel or Alternative Heating for Van Hot Water?

Some vans use diesel heating (like Webasto units) powered by the van's fuel tank. This is efficient for people who are comfortable with more complex systems, but it's not common in smaller van conversions. For most builds, propane (via Truma or standalone heaters) is the standard.

How Do You Install and Ventilate a Van Water Heater?

Any propane-burning heater needs proper ventilation and safety clearances. Installation requires:

Ventilation and Exhaust

Propane heaters produce carbon monoxide and water vapor. They need to exhaust outside the van. A vent pipe runs from the heater to the van roof, ensuring exhaust goes outside. Without proper venting, CO builds up inside and is dangerous. Every installation must include a CO detector as a safety measure.

Clearances and Spacing

Heaters need clearance from flammable materials (insulation, upholstery, wiring). Installation includes fireproofing and proper spacing. Mounting is usually on an exterior wall with insulation around it.

Propane Connections

The heater connects to the van's propane tank via copper or stainless steel tubing. All connections use proper fittings and are tested for leaks. A gas leak is a serious safety hazard.

How Much Does It Cost to Run a Van Water Heater?

Propane heaters are efficient but consume propane. A van using propane for both heat and hot water might use 10-20 pounds of propane per week during winter or heavy use. At current propane prices ($3-4 per pound), that's $30-80 per week — roughly $150-350 per month if actively heating.

Tankless heaters are more efficient than tank heaters (no standby heat loss). Truma Combi is efficient for dual-use. Electric heating (when plugged in) is cheap per BTU but requires shore power.

How Do You Winterize a Van Water Heater?

If you're parked in freezing weather without heating, you need to winterize your water heating system.

Draining the Heater

If the water heater isn't running, drain it before temperatures drop below freezing. Any water inside will freeze and crack the tank or burst lines. Most heaters have a drain plug on the bottom for this purpose.

Insulation for Cold Weather

If the van is heated, the water heater is usually inside or well-insulated, so freezing isn't an issue. The propane tank itself is protected by its design. The main concern is the external vent — ice can block it, reducing heater function. Keeping it clear is important.

How Much Does a Van Water Heater Cost?

Water heating costs vary significantly:

The Truma Combi is more expensive upfront but is a complete climate and hot water solution. For vans that need both heating and hot water (most full-time builds), it's the best value long-term.

What Are Common Van Water Heater Mistakes?

Undersizing the Heater

People buy a small tank heater to save money, then can't take a full shower without running out of hot water. You'll use your water heater every day — buy adequate capacity. A 20-gallon minimum for anything more than solo use.

Choosing Electric Only

Electric water heaters don't work when boondocking. If you plan to leave campgrounds, you need propane capability. The Truma Combi handles both gracefully.

Forgetting About Ventilation

A propane heater without proper ventilation is a carbon monoxide hazard. Every installation includes professional venting and a CO detector. Never skimp on this.

Not Winterizing

If you'll be parked in freezing weather, drain the heater. A burst tank is expensive to repair or replace.

How Do You Choose the Right Water Heater for Your Van?

Water heating choice depends on your lifestyle. Will you be plugged into shore power most of the time, or boondocking? Do you need interior heating as well? For most van conversions, the Truma Combi is the practical choice — it handles both and works efficiently whether you're plugged in or not.

We discuss this in the design phase. We ask: How important is a hot shower to you? How often will you be boondocking? What's your budget? Answers guide the recommendation.