Diesel Heaters

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Vehicle Diesel Heaters for Camper Vans – A Practical Guide

Diesel air heaters are a popular heating solution for camper vans, motorhomes and off-grid vehicles. They burn a small amount of diesel in a sealed combustion chamber and use a fan to distribute warm air through the cabin. This provides fast, reliable heat with low electrical consumption and no need for gas bottles.

Note: This page is provided for information only and you should have any vehicle heating system installed and maintained by a professional who knows exactly what they are doing. Exhaust fumes from Diesel heaters (Carbon Monoxide) are extremely dangerous and can silently kill, especially when sleeping in small environments such as campers and trucks. Always follow the manufacturers instructions to the letter and if you have any doubt, seek the assistance of a registered professional provider or engineer.

Manufacturers

A number of established manufacturers produce high-quality diesel heaters for recreational and commercial vehicles:

Eberspächer / Espar (Airtronic series) – A long-running German manufacturer widely used in OEM and aftermarket installations.
Webasto (Air Top series) – Another major OEM supplier known for robust auxiliary heaters used in RVs, trucks and boats.
Autoterm (formerly Planar) – A respected mid-range brand offering 2 kW and 4 kW heaters with widely available spare parts.
Planar, Timberline and other regional distributors – Often supply branded versions of Autoterm or OEM systems.
Unbranded/Chinese Diesel Heaters – Budget-friendly options commonly sold online. Performance can be acceptable, but documentation, QC and support may be inconsistent.

How Diesel Heaters Work

A typical diesel air heater includes:

A metering fuel pump drawing diesel from the main tank.
A combustion chamber with a glow plug for ignition.
A heat exchanger and fan that blows the warmed air into the cabin.
An external fresh-air intake and exhaust outlet with a silencer.

Because the combustion process is sealed, no fumes enter the living area. Correct installation of the exhaust and intake system is essential to ensure safe operation.

Installation Considerations

Installing a diesel heater requires mechanical, fuel-line and electrical work. Key points include:

Location – The unit must be mounted on a flat, stable surface with enough space for ducting and maintenance access.
Fuel Line – A dedicated feed from the diesel tank or auxiliary pickup point must be installed with proper filtration and secure clamps.
Exhaust & Intake Routing – Exhaust gases must be routed outside with correct clearances. The combustion air intake must not draw from inside the cabin.
Wiring – Units typically run on 12V and require appropriate fuses, switches and controllers.
DIY vs Professional – Experienced DIY owners often install their own heaters, but many choose professional fitting for safety, insurance and regulatory reasons.
Carbon Monoxide Alarm - A carbon monoxide alarm is vital when using a Diesel heater in your camper or truck. CO poising kills silently and quickly.

Maintenance

To keep a diesel heater operating safely and efficiently:

Perform an annual inspection or pre-winter service.
Check the exhaust for soot buildup or leaks.
Keep diesel clean by ensuring filters are changed when required.
Inspect electrical connectors for corrosion.
Carry spare glow plugs, fuses and a fuel filter for field repairs.
Heaters that are run frequently tend to stay cleaner internally, whereas rarely-used units may carbon up and require more frequent servicing.

Diesel Heater Troubleshooting Guide

Diesel Heater Maintenance Schedule

Running Costs

Fuel Consumption – A small 2 kW heater typically consumes 0.1–0.2 L/h on low settings; a 4 kW unit may reach 0.4–0.6 L/h at maximum output.
Electrical Draw – Generally low, often only a few amps during normal operation. Startup requires higher draw due to the glow plug.

For an overnight run of 8 hours at 0.2 L/h, a 2 kW heater uses around 1.6 litres of diesel—significantly cheaper than idling an engine or relying on electric heating off-grid.

Pros and Cons

Pros

Efficient heating using the existing diesel supply.
Fast warm-up and good heat distribution.
Low running cost and suitable for off-grid travel.
No need for propane cylinders or ventilation for open-flame appliances.

Cons

Installation is moderately complex (fuel, exhaust, electrics).
Branded heaters and professional installation add to upfront cost.
Poorly installed units can produce noise, smell or soot.
Incorrect installation poses safety risks—CO detectors are essential.

Safe Installation Checklist

Below is a comprehensive checklist suitable for DIY installers or for evaluating professional fits.

Pre-Installation Planning

Confirm heater size (kW rating) is appropriate for the vehicle.
Identify a safe mounting position away from fuel lines, sealed floors, and flammable materials.
Verify compliance with local regulations or insurance requirements.
Plan warm-air ducting routes and return-air paths.

Fuel System

Install a dedicated fuel pickup or tap into an approved auxiliary port.
Mount the fuel pump at the correct angle and height per manufacturer instructions.
Use proper heat-resistant fuel line and clamps.
Install a fuel filter in an accessible location.
Check for leaks after priming the fuel line.

Exhaust System

Use stainless steel exhaust components and high-temperature clamps.
Ensure exhaust exits outside the vehicle with safe clearances.
Do not route exhaust near moving parts or fuel lines.
Test for leaks with soapy water or by observing soot patterns.
Fit a heat shield if near sensitive materials.

Combustion Air Intake

Intake must draw from outside the cabin.
Fit a small mesh or guard to prevent debris ingress.
Keep intake and exhaust well separated to avoid recirculation.

Electrical System

Fuse the heater circuit appropriately close to the battery.
Use correct gauge cabling for current draw and cable length.
Protect the wiring in conduit where possible.
Ensure the controller/thermostat is mounted accessibly.
Confirm all connections are secure and corrosion-free.

Testing & Commissioning

Prime the fuel system according to the manual.
Run the heater through a full cycle (start, high, low, shutdown).
Check for abnormal noise, vibration or smoke.
Verify warm-air distribution and airflow.
Fit a carbon monoxide detector in the cabin.

Post-Installation

Record installation details for insurance/warranty.
Schedule annual maintenance.
Carry spare parts (glow plug, fuse set, fuel filter).

Typical Components

"1" Cool air inlet
"5" Warmed air outlet
"Airtronic" - Main body of the heater containing the ECU, Burner and Fan
'8" fresh air inlet for burner
"9" Exhaust outlet from burner
"12" Fuel pump
"24" Fuses

Picture copyright Eberspächer

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