How much fuel does a van air heater use?

A Webasto Air Top 2000 STC runs up to 22 hours on one gallon of fuel; an Air Top EVO 40 runs up to 16 hours per gallon at higher output.

Can I use a closeable louver on my heater ducting?

Not on a single-outlet ducted system. Webasto warns that restricting airflow during operation causes an overheat condition and can damage the heater. Use at least two outlets, or fixed adjustable louvers.

Do diesel heaters work at high altitude?

Espar AS3 full kits include an altitude sensor and operate to roughly 13,120 feet (4,000 m), which prevents rich running and sooting at elevation.

Can a Ford Transit run a diesel air heater?

It requires dropping the fuel tank and adding a fuel pickup pipe, so we do not offer a diesel Transit kit. Gasoline Transit and E-Series owners can use the Webasto 2 kW kit with its OEM-grade push-lock tank connector.

Diesel & Gasoline Van Air Heaters

Diesel & Gasoline Air Heaters for Camper Vans

Q: Will a diesel heater drain my house batteries overnight?

No. Running draw on an Espar AS3 is 6 to 26 watts, so an eight-hour night uses well under 200 Wh, far less than a compressor fridge.

Q: Can I install a gasoline heater on a diesel van?

No. Burner design, fuel pump metering and ignition are fuel specific. Match the heater to the tank you are tapping.

A fuel-fired air heater is the single best comfort-per-amp upgrade in a van. Ours pull 6–26 watts running — you can heat a van all night on almost no battery, which is why we install them in nearly every build that leaves our Roanoke shop, even ones with big lithium banks. This collection is the genuine article: Espar (Eberspächer) AS3 D2L diesel and B2L gasoline full kits with real Eberspächer harnesses, and Webasto Air Top 2000 STC and Air Top EVO 40 kits assembled by an authorized North American distributor with full factory warranty support. The Webasto kits come with vehicle-specific fuel tank tap kits for ProMaster, Sprinter, and Transit, plus a noise suppression package of genuine Webasto exhaust muffler, intake silencer, stainless tubing, and hangers — the parts that separate a heater you can sleep next to from one you can hear from the campsite next door. We also stock the 60mm and 90mm louvers, tees, clamps and 22mm exhaust mufflers you need to finish the ducting properly.

How to Choose a Van Air Heater

1. Fuel type is decided by your van, not your preference

If you're on a diesel Sprinter, run a diesel heater off the main tank. If you're on a gas Transit or gas ProMaster, run a gasoline heater. Mixing is not worth it. Two fitment realities to know before you buy:

Diesel Ford Transit: installing a diesel heater requires dropping the fuel tank and adding a pickup pipe. We don't offer an Espar diesel Transit kit for that reason. Gasoline Transit owners get the clean path — the Webasto 90-3-0026 kit includes an OEM-grade push-lock tank connector for Transit/E-Series gasoline.
2021+ gasoline Sprinter: the Webasto push-lock fuel tank tap does not fit. That tank has to be drilled for a standpipe. Know this before you're under the van on a Saturday.

Sprinter and ProMaster both have an unused factory auxiliary fuel port; our Webasto 10-7-0010 tap kit clicks straight onto it. Espar kits ship with a fuel standpipe (not a T-piece) and hoses sized for the factory auxiliary port — many builders also source the Dorman 800-188 adapter for convenience.

2. 2 kW or 4 kW — output vs. cycling

Bigger is not better. An oversized heater in a well-insulated van short-cycles, which is noisy and hard on the burner.

Webasto Air Top 2000 STC (2 kW): 3,070–7,000 BTU, up to 22 hours on a gallon of fuel, 60mm ducting. This is the right heater for a 144" Sprinter, a 136"/159" ProMaster, or a 148" Transit that has Thinsulate in the walls.
Webasto Air Top EVO 40 (4 kW): 5,800–11,942 BTU (1.7–3.5 kW, boost to 4 kW), up to 16 hours per gallon, 90mm ducting. Choose it for a 170" EXT, a poorly insulated cargo shell, a build with lots of glass, or genuine sub-zero use.
Espar AS3 D2L / B2L (2 kW class): compact body, easy placement, Easy Start Pro controller included.

3. Altitude compensation matters more than people think

Both Espar AS3 kits include an altitude sensor and operate to roughly 13,120 ft (4,000 m). If you spend time in the Rockies or the Sierra, that's not a luxury — a combustion heater without altitude compensation runs rich, sooties the burner, and eventually throws a fault at exactly the moment it's coldest.

4. Plan the ducting before you pick a mount location

Duct diameter is set by the heater: 60mm for AT2000-class, 90mm for EVO 40. Rules we work by:

Keep runs short and sweeping. Every tight bend is static pressure the blower has to fight.
Put an outlet at the foot of the bed and one low in the living area. Heat rises; don't duct into a ceiling.
Do not use a closeable louver on a single-outlet ducted system. Webasto is explicit: restricting airflow during operation causes an overheat condition and can damage the heater. If you want a closeable louver (1320206A, 9012300A, 1320355A) run at least two outlets, or use fixed adjustable louvers (1320204A, 1322405A, 1320709A) and a tee (1320474A).
Return air needs a path. An air inlet grate (87389A) in a cabinet face keeps the heater from starving behind a panel.

5. Exhaust and intake are a safety system, not an afterthought

Route the exhaust downward and away from any opening — doors, roof vents, windows. Use the stainless muffler (22mm 1320488A for 22mm-port heaters; the kits include a 24mm muffler where appropriate), clamp both ends, and support the run with mounting hangers so vibration doesn't crack a joint. Webasto confirms the muffler can be mounted in either flow direction. Add a CO alarm regardless of how clean the install looks.

6. Install skill level

These kits are designed for someone with intermediate mechanical skill and basic tools. The hard part is not the electrical — it's the fuel tap and the exhaust hangers, both of which happen on your back under the van. Some vehicles give you tank port access through a removable floor panel; others don't. If you'd rather have it done, we install these in Roanoke.

Frequently Asked Questions

Will a diesel heater drain my house batteries overnight? No. Running draw on the Espar AS3 is 6–26 W. Startup glow-plug draw is higher for a couple of minutes, but over an eight-hour night you're looking at well under 200 Wh — a rounding error next to a fridge. This is exactly why we pair heaters with modest power systems and save the big battery banks for air conditioning.

How much fuel does a van heater actually use? The Air Top 2000 STC gets up to 22 hours on one gallon; the EVO 40 gets up to 16 hours on a gallon at its higher output. In practice, cycling in a well-insulated van, most owners burn a gallon every two to four nights of shoulder-season use.

Can I install a gasoline heater on a diesel van, or vice versa? No. The burner, fuel pump metering, and glow element are fuel specific. Match the heater to the tank you're tapping.

Why are your kits more expensive than the ones on Amazon? Because they're genuine Webasto and Eberspächer units with factory harnesses and warranty support, and because we add the parts a good install actually needs: the stainless muffler, intake silencer, extra meter of exhaust tube, mounting clips and hangers, and the vehicle-specific fuel tank tap. Cheap clone heaters skip the noise suppression entirely and their controllers are the first thing to fail. When a clone dies in February there's no distributor to call.

Do I need to re-duct if I later add air conditioning? No — a fuel heater and a rooftop A/C or heat pump are independent systems. Plenty of our customers run both: the heater for real cold and off-grid nights, the heat pump for mild shoulder weather when it's cheaper to move heat than burn fuel. Heat pumps lose capacity as it gets colder; a combustion heater doesn't care.

What about the Pundmann Therm water heaters you carry — are those the same thing? Different job. The Pundmann Therm units (3L, 6L, 9L, and the 10L 4-in-1) heat domestic water on 12V and 110V, and the 4-in-1 also takes engine heat and provides air heat. If you want hot showers, that's the product; if you want to heat the cabin, buy the air heater.