Fitting a Diesel Heater
A comprehensive guide to choosing and installing a diesel heater in your campervan — from budget Chinese units to premium Webasto and Eberspacher systems.
Why Choose a Diesel Heater?
A diesel heater is widely considered the best heating solution for UK campervans. Unlike gas heaters, they draw fuel directly from your van's diesel tank (or a small separate tank), produce dry heat that doesn't create condensation, and are incredibly fuel-efficient — typically using just 0.1 to 0.25 litres per hour. On a cold January night in the Lake District, a diesel heater will keep your van at a comfortable 20°C while barely making a dent in your fuel.
The main decision you'll face is whether to invest in a premium brand (Webasto or Eberspacher) or go with a budget Chinese unit. Both work on the same principle — burning diesel to heat air which is then blown into your living space through ducting. The difference lies in build quality, noise levels, reliability, and certification.
Dry Heat
No condensation — unlike gas heaters that produce moisture
Fuel Efficient
0.1–0.25 L/hr — a full tank lasts weeks of heating
Safe
Combustion happens outside the van — exhaust vents underneath
Heater Comparison
| Heater | Output | Fuel Use | Price | Quality |
|---|---|---|---|---|
| Webasto Air Top 2000 STC German | 0.9 – 2.0 kW | 0.12 – 0.24 L/hr | £800 – £1,200 | ★★★★★ |
| Eberspacher Airtronic D2 German | 0.9 – 2.2 kW | 0.10 – 0.28 L/hr | £700 – £1,100 | ★★★★★ |
| Chinese Diesel Heater (Generic) China | 2 – 5 kW (typically 2kW used) | 0.10 – 0.50 L/hr | £80 – £200 | ★★★☆☆ |
| Planar 2D / Autoterm Air 2D Russian/Estonian | 0.8 – 2.0 kW | 0.10 – 0.24 L/hr | £400 – £600 | ★★★★☆ |
Installation Guide — Step by Step
Plan the Installation
Choose the heater location, plan ducting routes, and identify where the exhaust will exit. The heater unit is typically mounted under the van floor or inside a sealed compartment.
- Mount the heater as close to the fuel tank as practical
- Ensure the exhaust exits away from any openings (windows, vents)
- Plan for at least one warm air outlet in the living area
- Consider noise — mount away from the sleeping area if possible
Cut the Floor Hole
Mark and cut the mounting hole in the van floor for the heater unit. This is typically a rectangular cutout that the heater body drops through.
- Use the supplied template for accurate marking
- Drill pilot holes at corners before cutting with a jigsaw
- Apply rust treatment to all cut edges immediately
- Double-check clearance from fuel lines, brake lines, and the exhaust
Mount the Heater Unit
Secure the heater to the floor using the mounting plate. The unit should be level and firmly fixed with no vibration.
- Use the supplied mounting gasket for a weatherproof seal
- Tighten bolts evenly in a cross pattern
- Ensure the heater is level — this affects fuel flow
- Apply sealant around the mounting plate edges
Install the Exhaust System
Connect the exhaust pipe to the heater outlet and route it to exit underneath the van. The exhaust must point downward and away from the van body.
- Use only the supplied exhaust pipe — never substitute
- Ensure all joints are properly clamped with exhaust clamps
- The exhaust exit must be at least 250mm from any opening
- Route the exhaust away from plastic components and fuel lines
- The exhaust must exit pointing downward to prevent water ingress
Connect the Fuel Supply
Install the fuel pickup from your van's diesel tank (or a separate tank) and connect it to the heater's fuel pump. The fuel pump is usually mounted under the van.
- Use automotive-grade fuel line (replace cheap Chinese fuel line)
- Mount the fuel pump at a 15–35° angle as per instructions
- The fuel pump should be lower than the fuel tank
- Use proper fuel line clamps — not cable ties
- Bleed the fuel line before first startup
Install Ducting and Outlets
Connect the warm air ducting from the heater outlet to your interior vents. Use 60mm or 75mm ducting depending on your heater model.
- Use insulated ducting where it passes through cold areas
- Keep duct runs as short and straight as possible
- Install at least one adjustable vent in the living area
- A Y-splitter can distribute heat to two areas
- Secure ducting with proper clamps — not cable ties
Wire the Electrics
Connect the heater to your 12V leisure battery system. Install the controller/thermostat in a convenient location.
- Use at least 2.5mm² cable for the power supply
- Install an inline fuse (typically 15A) near the battery
- Mount the controller where you can reach it from bed
- The heater draws 10-30W when running, plus ~100W on startup
- Wire directly to the leisure battery — not through the consumer unit
Install CO Alarm and Test
Before running the heater, install a carbon monoxide alarm inside the van. Then perform a careful first startup and check for leaks.
- Install a CO alarm at head height in the sleeping area
- Run the heater for 30 minutes on first startup (it will smoke initially)
- Check all exhaust joints for leaks using soapy water
- Monitor the CO alarm during the first few hours of use
- The initial burn-off smell is normal and will fade
Safety Checklist
Complete every item on this checklist before running your diesel heater for the first time.
- Carbon monoxide alarm installed at head height in sleeping area
- Exhaust system fully sealed with no leaks
- Exhaust exit at least 250mm from any opening (windows, vents, doors)
- Exhaust pointing downward to prevent water ingress
- Fuel connections leak-free with automotive-grade fuel line
- Inline fuse installed on the power supply
- Adequate ventilation in the van (do not seal all openings)
- Fire extinguisher accessible near the heater area
- Heater mounted level and securely fixed
- No combustible materials within 100mm of the heater or exhaust
Typical Costs
| Item | Budget Build | Mid-Range | Premium |
|---|---|---|---|
| Heater unit | £80 – £150 | £400 – £600 | £800 – £1,200 |
| Ducting & vents | £20 – £40 | £30 – £60 | £50 – £100 |
| Fuel line & fittings | £15 – £30 | £20 – £40 | £30 – £50 |
| CO alarm | £20 – £30 | £20 – £30 | £20 – £30 |
| Miscellaneous (sealant, clamps, wire) | £20 – £40 | £30 – £50 | £40 – £60 |
| Total (DIY install) | £155 – £290 | £500 – £780 | £940 – £1,440 |
Where to Buy
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