How to Install a Diesel Heater in a Camper Van or RV

To install a diesel heater, plan everything around one rule: the combustion air intake and the exhaust must both be outside the vehicle. The exhaust pipe must be well sealed and end away from windows and air intakes. The location, fuel supply, wiring and every dimension come from your heater’s manual. Fit a CO alarm, and hire an installer for any step you cannot do with confidence.

This guide covers the decisions and the checks, not a wrench-by-wrench procedure. Kits differ, and we have not installed these heaters ourselves, so your manual is the authority for parts and measurements.

Should I install it myself or hire a pro?

Do the planning yourself; hand the safety-critical work to a professional unless you have done it before. A mistake in the exhaust, fuel or high-current wiring can cause a CO leak, a fuel leak or a fire.

Task	DIY-friendly?	Why
Choosing size and format	Yes	Uses calculators and the listing
Planning location and duct runs	Yes	Measuring and checking the manual
Drilling the floor for intake and exhaust	Only with experience	Must avoid frame, fuel and brake lines under the floor
Tapping the vehicle fuel tank	Installer	Fuel leaks and tank damage are hard to undo
Wiring and fusing to the battery	Only with experience	High start-up current; fuse and cable sizes from the manual
Paperwork and insurance	Yes	Ask your insurer before you start

Fixed install or all-in-one?

A fixed install is cleaner and permanent; an all-in-one avoids drilling but lives outside.

	Fixed install	All-in-one
Where it sits	Inside, under a seat or in a box, per the manual	Outside the vehicle, or inside only if the exhaust is routed out
Intake and exhaust	Through the floor to outside	From the box, outside
Fuel	Separate tank or vehicle tank	Built-in tank
Work involved	Drilling, sealing, wiring	Duct through a window or panel
Example	OBAKL OAH-B2	VVKB Apollo-P2

The all-in-one rule is strict: the box stays outside, or the exhaust goes outside, and only the warm-air duct comes in. Never with the exhaust inside.

How do I plan the install, step by step?

Work through these steps before you drill anything, and check each against your manual.

1. Size the heater. Estimate the output you need with the heater size calculator. Most vans need well under 5 kW, so a 5 kW unit will run mostly on low. Our guide on what size heater you need explains why oversizing hurts.
2. Check the specs add up. One liter of diesel holds about 10 kWh, so maximum fuel use × 10 caps the real output. Avoid units whose claims break that rule.
3. Choose the location. Pick a spot the manual allows, where the intake and exhaust can pass straight through the floor to the outside. Keep it clear of bedding and stored items.
4. Map the underside. Before any hole, look under the floor for the frame, fuel lines, brake lines and wiring. If you cannot see clearly, stop and ask an installer.
5. Route intake and exhaust outside. Both pipes go outside. The exhaust must be sealed at every joint, end away from windows, doors and air intakes, and not point at the intake. Follow the manual’s lengths and clamps.
6. Plan the fuel supply. Either a separate tank from the kit or a pickup in the vehicle tank. Tapping the vehicle tank is an installer job.
7. Plan the power. The heater needs a fused 12 V (or 24 V) supply from your battery, with cable and fuse sizes from the manual. Account for the glow plug’s start-up peak.
8. Plan the warm-air ducting. Short runs lose less heat. Aim the outlet where you sit and sleep.
9. Fit the CO alarm. Mount it where the alarm’s maker recommends, and test it. See the best RV carbon monoxide detectors.
10. First start, supervised. Run the first cycles with doors open and the CO alarm on. At any smell of exhaust or fuel, switch off and get the install checked.

What does a diesel heater need from my battery?

A short peak at start-up, then a much lower draw while it runs. The glow plug heats the combustion chamber for a few minutes and pulls the most current then. Once the flame is stable, the fan and fuel pump draw far less.

None of the seven diesel heaters in our US catalog publishes its running draw, so take the figure from your manual. Frequent starts and stops use more battery and build more carbon. A thermostat mode that keeps the heater on low is gentler on both. The diesel heater fuel calculator turns fuel range, draw and hours into liters and amp-hours per night; replace its default values with your manual’s figures.

What you know	Formula	Example
Running draw in W	Ah = W × hours ÷ volts	20 W × 10 h ÷ 12 V ≈ 17 Ah
Fuel range in L/h	Liters = average L/h × hours	0.3 L/h × 10 h = 3 L
Tank size	Nights = tank ÷ liters per night	15.1 L ÷ 3 L ≈ 5 nights

The example values are illustrations, not specs of any model.

What about ECE R122, inspections and insurance?

ECE Regulation No. 122 is the UN/ECE rule for vehicle heating systems. It covers exhaust gases, fuel tightness, surface temperatures, shutdown if the flame fails and overheating (EUR-Lex). A heater with a declared approval makes paperwork easier where it applies.

None of the listings we cover declares R122 approval, so do not assume one has it. Before you drill, ask your insurer whether they need anything, and check any inspection rules that apply to your vehicle.

How do I keep it running cleanly?

Size it right, avoid constant restarts and run it on a steady low setting. An oversized heater cycles on and off, and each start costs battery and adds carbon. A heater that runs steadily at a low output tends to stay cleaner.

• Match output to your space with the calculator.
• Use thermostat mode where your controller offers it.
• Keep the exhaust and intake clear of mud, snow and debris.
• Watch the CO alarm and test it regularly.
• Get it serviced by a heater specialist if it smokes, smells or starts poorly.

Which heaters make the install easier?

Units that include the exhaust parts, a large tank or an all-in-one case remove the most guesswork. The ICECOSMOS VH08 PRO includes an exhaust pipe and muffler. The OBAKL OAH-B2 has a 15.1 L (4 gal) tank and, per its listing, a pickup to draw from the vehicle tank. The VVKB Apollo-P2 is an all-in-one with a 5 L tank and no drilling.

Compare all seven in the best diesel heaters, or see how diesel stacks up against propane and electric in our camper heaters hub. For the full safety picture, read carbon monoxide in campers.