Diesel heater for vans and campers

How a diesel heater works

A diesel heater burns fuel in a sealed combustion chamber, then sends the exhaust outside while a separate airflow passes over a heat exchanger and into the cabin. Because the combustion and cabin air are isolated, the heater delivers dry, fume free warmth that reduces condensation inside the vehicle. Air heaters move warm air through ducting, while hydronic heaters heat coolant that feeds fan coils or a floor loop and can also prewarm an engine block. Both styles sip fuel and run on twelve volt power, which makes them ideal for off grid use.

Startup uses a glow element to ignite fuel, then a metering pump maintains a controlled burn. Once at temperature, the heater modulates output to hold a setpoint or to maintain a selected fan level. The result is steady heat with less moisture than propane space heaters that vent indoors. With correct installation, cabin air quality remains high and carbon monoxide risk is mitigated by the sealed design and outdoor exhaust.

Sizing, output, and fuel use

Right sizing a diesel heater begins with interior volume, insulation, window area, and the lowest temperatures you expect to face. Many vans are well served by two to three kilowatt air heaters, while larger campers or cold climate travelers may prefer a four to five kilowatt unit. To translate, one kilowatt is about three thousand four hundred BTU, so a five kilowatt heater approaches seventeen thousand BTU at full power. Oversizing can lead to short cycling and carbon buildup, while undersizing may never catch up on icy nights.

Fuel consumption is modest. At low to medium output, typical air heaters use roughly one tenth to a quarter liter of diesel per hour. Electrical draw peaks briefly at startup, often eight to ten amps for a couple of minutes, then settles to about one amp or less during steady operation depending on fan speed and controls. Many controllers offer thermostat modes, timers, altitude settings, and diagnostic readouts to keep performance consistent.

Altitude matters. Above two thousand meters, thin air requires less fuel per combustion cycle to maintain the right mixture. Some heaters auto adjust; others need a manual setting. Without proper tuning, the flame runs rich, soot accumulates, and efficiency falls. If your travel plan includes high passes, confirm the heater supports altitude compensation.

Noise character comes from three sources. The fan produces a steady whoosh, the exhaust can drone without a muffler, and the metering pump ticks as it pulses fuel. Placement, rubber isolation mounts, a quality exhaust silencer, and strategic duct routing can make a dramatic difference in perceived sound.

Placement, safety, and maintenance

Installers usually place an air heater near the floor to capture the stratification benefit and keep duct runs short. The combustion intake and exhaust must exit outside with sufficient clearance from doors and windows. Keep the intake away from road spray and the exhaust pointed downward and aft, with a drip loop and proper heat shielding. Maintain separation between combustion intake and cabin air intake to prevent recirculation of fumes.

Fuel can be drawn from a dedicated tank or tapped from a vehicle tank at a higher pickup point so the heater cannot run the vehicle dry. Use rated hose, clamps, and a tidy routing plan with a gentle rise to the heater. The metering pump is typically mounted on a slight angle to reduce air bubble issues. Electrical connections need clean power, fusing, and proper gauge wiring to handle startup load.

Safety essentials include a carbon monoxide detector, smoke alarm, and a small ABC fire extinguisher within reach. Because the combustion circuit is sealed and exhausted outside, CO risk is low with a proper install, but sensors provide peace of mind. Duct temperatures near the heater outlet can be very hot, so use heat rated materials and guards near feet or soft goods.

Maintenance is straightforward. Run the heater on high for fifteen to thirty minutes periodically to burn off deposits. Inspect the exhaust, intake, and fuel lines seasonally. If your controller shows repeated flameouts or you see excessive smoke, a service of the glow element and burner screen may be due. Clean intakes keep airflow strong and reduce creaking noises from hot ducts.

Choosing air or hydronic

Air heaters deliver rapid, simple heat with minimal components, which suits most van interiors. Hydronic systems shine when you want multi zone comfort, heated floors, or engine preheat for cold starts. A hybrid approach can combine an air heater for quick warmups with a small hydronic loop for targeted areas like a shower room or a bench. Consider service access, plumbing complexity, and how you actually live inside the space before committing to either path.

Controls, ducts, and comfort tuning

Thermostat based control targets a room temperature and modulates output automatically, which feels familiar and saves fuel. Fan level control holds a constant output and can be quieter in mild weather. Thoughtful duct placement sends warm air to cold surfaces such as slider doors and large windows, which reduces condensation and removes that chilly wall effect. A short return path for cabin air back to the heater improves efficiency by recirculating warm air rather than constantly heating cold outside air.

When to service and common symptoms

If you notice smoky startups, frequent restarts, or a loss of maximum output, carbon buildup or poor combustion air may be the cause. Long periods of idling on low without periodic high power burns can contribute. Altitude trips without adjustment often leave soot behind. Gentle cleaning of the intake filter, inspection of the glow screen, and fresh gaskets during service can restore crisp ignition and clean exhaust. A rhythmic rattle may point to exhaust contact with the body or a loose clamp, while louder ticking from the pump can be quieted with rubber mounts.

Professional installation and integration

Heating is only as good as the system that supports it. A professional team can integrate the diesel heater with your fuel system, house batteries, and interior layout so it runs quiet, sips power, and stays serviceable. Insulation, vapor barriers, and window treatments matter just as much as heater size, and clean carpentry around ducts prevents hot spots and rattles.

Custom build van heating packages

If you want heat planned into a full interior, explore our custom build van options that pair a diesel heater with power management, ventilation, and moisture control. See our page for a custom build van to understand how heating fits into a complete layout.

Mainstream vans upgrades

Already have a platform and need a tidy heating solution that respects book value and financing needs. Our team specifies heater size, placement, and controls for popular models. Learn more on mainstream vans.

Start your cold weather plan

If you are planning shoulder season trips or winter mountain runs, we can design and install a diesel heater as part of a balanced cabin comfort plan that includes airflow and insulation. Begin with our hub for recreational vans and we will map the right path for your travel patterns.

What we do and how to get started

OZK Customs designs and builds recreational adventure vans, overland upfits, and towable interiors with an emphasis on real world use. We integrate diesel heaters, electrical systems, ventilation, cabinetry, and storage that can handle life on the road. We do not rent vehicles and we do not sell footwear. If you are ready for warm, dry nights and an interior that works as hard as you do, reach out and we will build a plan around your routes and your crew.

Ready for warm, dry heat on every trip. Book a design consult to spec, install, and dial your diesel heater with OZK Customs. Our team integrates fuel, power, and controls for quiet, reliable performance. Start your build plan now.