Diesel vs. Gas Air Heaters for Vans
The short answer: buy the heater that burns what is already in your van's tank. A diesel air heater and a gasoline air heater are the same machine — same sealed combustion chamber, same 12 V blower, same 4–27 W running draw, same thermostat — differing mainly in the burner and the fuel it is calibrated for. Carrying a second fuel type so you can run the "better" heater is a bad trade in a vehicle where every litre of storage is contested.
There is one large exception, and it is the whole reason this guide exists: on a 2015+ Ford Transit, a diesel air heater requires dropping the fuel tank to add a pickup. We do not sell a Transit diesel kit for that reason. If you own a diesel Transit, the honest options are a professional install with a tank drop, or a separate day tank. On a gasoline Transit, the factory auxiliary port makes the install straightforward.
Last updated 8 September 2026 by the build team at Noke Van Co., Roanoke, Virginia. We install these heaters for a living.
Start here: what your van will accept
This table decides the purchase for most people. It reflects what is actually in the box of the kits we stock.
| Van | Diesel | Gasoline | Fuel-tap reality |
|---|---|---|---|
| Mercedes Sprinter 2007+ (NCV3 and VS30) | Espar AS3 D2L full kit — $1,525 | Espar AS3 B2L full kit — $1,600; Webasto EVO 40 4 kW kit — $2,598.26 | Kit ships with a fuel standpipe. Hoses are made to clamp onto the factory auxiliary port; a Dorman 800-188 auxiliary fuel connector is an optional convenience. |
| Ram ProMaster 2014+ | Espar AS3 D2L full kit — $1,525 | Webasto Air Top 2000 STC 2 kW kit — $1,870.45; Webasto EVO 40 4 kW kit — $2,598.26 | Auxiliary fuel port sits under the cab floor entry. The Webasto kits include our custom push-lock tap that clicks straight onto the unused factory port. |
| Ford Transit 2015+ / E-Series | Not offered. Requires dropping the tank and fitting an additional pickup. | Webasto Air Top 2000 STC 2 kW kit — $1,874.69; Webasto EVO 40 4 kW kit — $2,399.10 | Gasoline kits include our 10-7-0011 push-lock tap for the factory auxiliary port. No tank drop. |
Before you buy anything for a diesel van, note the standing advice from both manufacturers and from us: have a licensed builder or mechanic review the fuel-side installation on diesel models. Tapping a modern common-rail return or supply circuit incorrectly is not a mistake you find out about gently.
Everything on this page lives in van air heaters.
What the two fuels actually change
Set aside the marketing. Here is the engineering.
They are the same machine
Both burn liquid fuel in a sealed metal chamber, isolated from your living space. A dosing pump meters fuel in single measured pulses, a glow pin ignites it, a combustion-air blower feeds the flame from outside the van, exhaust exits under the vehicle, and a completely separate cabin blower pushes your interior air across the outside of the hot chamber. No combustion product touches the air you breathe, and no water vapour is added to the cabin. That last point is why air heaters beat unvented propane in a van: propane produces roughly a litre of water per litre of fuel burned, and in a sealed insulated box that water ends up on your windows and inside your walls. If you are already fighting condensation, read why van condensation happens.
Where they differ
Cold weather favours gasoline — genuinely. Number 2 diesel begins to cloud and gel somewhere around 15 °F depending on blend. Filling with winter-blend fuel or dosing anti-gel handles it, but a gasoline heater has no gel point to worry about. If you spend February at altitude in the Rockies, that is a real, if manageable, advantage.
Soot favours diesel discipline. A diesel burner run for weeks at its minimum output never gets hot enough to burn off carbon, and deposits build on the burner screen and glow pin until the unit starts throwing flame-out codes. The fix is trivial and almost nobody is told about it: run the heater at full output for 20–30 minutes every few weeks. Gasoline units are less prone to this specific failure.
Service life and parts favour diesel. The diesel D-series is the volume product across commercial trucking; parts, dealers and technicians are everywhere, and burner and glow-pin life is generally longer than on the gasoline B-series. Gasoline is also the more volatile fuel, so the fuel-line routing, the standpipe seal, and heat separation matter more; vapour lock in a line run too close to an exhaust is a gasoline-specific failure mode.
Price favours diesel, slightly. $1,525 vs. $1,600 on the like-for-like Espar AS3 pair. Not enough to change anyone's decision.
Net: if you own a diesel van, buy diesel. If you own a gasoline van, buy gasoline and do not feel short-changed — the gasoline units work, we install them constantly, and the alternative of carrying a jerrycan of diesel to feed a heater is worse in every way.
The numbers, side by side
| Espar AS3 D2L (diesel) | Espar AS3 B2L (gasoline) | Webasto Air Top 2000 STC | Webasto Air Top EVO 40 | |
|---|---|---|---|---|
| Our kit price | $1,525 | $1,600 | $1,870–$1,875 | $2,399–$2,598 |
| Heat output | 7,500 BTU (2.2 kW) | 2 kW class | 3,070–7,000 BTU (1–2 kW) | 5,800–11,942 BTU (1.7–3.5 kW, boost to 4 kW) |
| Fuel burn | 0.04–0.07 gal/h | comparable | up to 22 h per gallon | up to 16 h per gallon |
| Electrical draw, running | 4–27 W | 6–26 W | low, comparable | low, comparable |
| Start-up surge | glow plug ~30 A for the first minute or two | same | same order | same order |
| Altitude | automatic compensation to 13,120 ft (4,000 m) | automatic to 13,120 ft | confirm sensor variant for your kit | confirm sensor variant for your kit |
| Ducting | 60 mm | 60 mm | 60 mm | 90 mm |
| Control | Easy Start Pro | Easy Start Pro | Smartemp 3.0 Bluetooth | programmable Smartemp 3.0BT |
| Weight | 5.5 lb (2.5 kg) | 5.5 lb | comparable | heavier |
What those numbers mean in a night
At 0.04–0.07 gal/h, twelve hours of cycling on a cold night costs roughly half a gallon of fuel. A week of hard winter use is around four gallons. Against a full Sprinter tank that is noise — which is exactly the point of tapping the vehicle tank rather than carrying fuel.
Electrically it is even better. At 4–27 W running, a full night of heating costs about 150–250 Wh including the glow-plug starts (roughly 30 A × 12 V for 90 seconds is about 9 Wh per start). Compare that with resistance heating: a 1,500 W electric heater for eight hours is 12 kWh — nearly the entire usable capacity of a 15 kWh lithium bank. There is no version of van life where electric space heating makes sense off-grid. If you want the full load-budget arithmetic, see how to size a campervan electrical system.
One caution on that surge: the glow pin draws around 30 A for a minute or two at every start and again during the shutdown purge. Wire and fuse the heater exactly per the manufacturer's diagram, on its own circuit, with the harness supplied in the kit. Do not tee it into a shared accessory circuit, and do not run it from a small portable power station whose output limit is below the surge.
2 kW or 4 kW? Almost everyone over-buys
The most common mistake we see is a 4 kW heater in a well-insulated 144 Sprinter.
Estimate the load rather than guessing. Heat loss is roughly:
Q (BTU/h) = envelope area (ft²) × ΔT (°F) ÷ assembly R-value
A 144 high-roof cargo interior has on the order of 250 ft² of walls, ceiling, floor and doors. Insulated with 3M Thinsulate at 44 mm you have a nominal R-9.4 in the cavity, but ribs, compression at the fastening points and the sheer number of penetrations pull the assembly value down to something like R-5. At a 40 °F temperature difference — 30 °F outside, 70 °F inside:
250 × 40 ÷ 5 = 2,000 BTU/h
Add glass and air leakage, generously 30–50%, and you land near 2,800–3,000 BTU/h.
A 2 kW heater makes 7,000 BTU/h at full output and 3,070 BTU/h at minimum. So on a 30 °F night, a properly insulated 144 needs a 2 kW heater to run at just above its minimum setting. A 4 kW unit in that van spends the entire night short-cycling: fire, overshoot, shut down, cool, fire again. Short-cycling is loud, it is the fastest route to a sooted burner, and it wastes more fuel than continuous low-output running.
Buy 4 kW when:
- 170" or 170" EXT Sprinter, or a 148" EXT Transit
- large glazing area, or an uninsulated or lightly insulated shell
- routine use well below 0 °F
- long duct runs, or you are heating a rear garage as well as the living space
- box trucks, ambulances and anything with more than about 350 ft² of envelope
Buy 2 kW for basically everything else, and note the EVO 40 also steps you up to 90 mm ducting, which changes every fitting you buy.
Ducting, exhaust and the details that decide whether you like your heater
A well-chosen heater installed badly is a bad heater. These are the constraints that matter.
Duct runs. Keep them short and straight. A tight 90° bend in flex duct costs roughly the same static pressure as three feet of straight run, so a "short" duct with four elbows is not short. On a 2 kW unit aim to stay under about 6.5 feet of total equivalent length. Split with a proper 60 mm tee rather than a Y made of tape.
Return air is not optional. The cabin blower has to get air back. If the heater lives in a sealed bench with a supply duct and no return path, it starves, overheats and shuts down on a high-temperature fault. Fit an air inlet grate and leave the return path genuinely open.
Outlet placement. Heat rises, so put the outlets low — at floor level, ideally aimed along the floor toward the far end of the van. An outlet at head height gives you a hot face and cold feet. Use adjustable louvers so you can rebalance, and closeable louvers where you want to shut a zone off. For 90 mm systems, the 90 mm adjustable and 90 mm closeable versions are the equivalents. Everything is in Webasto heater parts.
Exhaust. It must exit outside the vehicle envelope and slope continuously downward from the heater so condensate drains out rather than back into the burner. Terminate it outboard and away from doors, opening windows, roof vents and any fresh-air intake — never under the slider where it will be drawn straight back in when you open the door. Exhaust tube runs several hundred degrees; keep real clearance from anything combustible, use the supplied stainless clips, and never cable-tie it to a brake or fuel line. Fit the stainless exhaust muffler — on the Espar it can be mounted in either flow direction, which the part itself does not tell you.
Combustion air. The intake must draw from outside the living space, be separated from the exhaust outlet so it cannot ingest its own exhaust, and be routed so it cannot fill with road spray. A 22 mm combustion air elbow keeps the intake pointed sensibly. Our Webasto kits include an intake silencer as part of the noise-suppression package, and it is worth fitting.
Fuel pump angle. The dosing pump must be mounted rising toward the heater at roughly 15° to 35°. Too flat and it airlocks; too steep and it cavitates. This single detail is behind a large share of "my heater won't start" calls.
Fuel line. Use only the supplied plastic fuel line — rubber degrades in contact with these fuels — keep it clear of the exhaust, support it every foot or so, and insulate exterior connections so they do not crack in winter. The standpipe in the tank is deliberately cut short of the bottom so the heater runs out of fuel before the engine does; confirm its length against your install manual so you know exactly how much reserve you keep.
Noise. People blame the burner. It is almost always the dosing pump. Its measured tick transmits straight into the structure it is bolted to. Mount it on a rubber isolator, on the underside of the floor rather than inside a cabinet, and away from the head of the bed. Our Webasto kits ship with a full genuine-Webasto noise-suppression set — muffler, clamps, an extra metre of stainless exhaust tube, hangers, intake silencer and tubing — precisely because that is what separates a heater you tolerate from one you forget is running.
Carbon monoxide alarm. Non-negotiable. Sealed combustion is safe until a seal or an exhaust joint is not. Fit a CO alarm at sleeping level, test it, and replace it on its expiry date.
The alternatives, briefly and honestly
Hydronic / combi. If you want cabin heat, domestic hot water and engine pre-heat from one appliance, the Pundmann Therm Air Flow Heat 10L 4-in-1 at $1,255 covers all three. It is a more complex install with more plumbing to winterise, and it makes most sense in a full-time four-season build. Simpler alternative: a dedicated air heater plus a Pundmann Therm boiler on its own.
Propane. A vented propane furnace is a legitimate product, but it means a propane locker, a regulator, a leak-detection plan, and a second fuel to source on the road. We do not stock propane space heaters.
Electric. Covered above: 12 kWh a night. No.
Cheap unbranded diesel heaters. They work until they don't, and the failure modes are the ones that matter — burner seals, exhaust fittings, and controllers that don't fault correctly. We sell genuine Eberspächer and genuine Webasto units with harnesses from the manufacturer and warranty support from an authorised North American distributor, because a sealed combustion appliance running while you sleep is the wrong place to save $600.
Choosing, in three lines
- Diesel van → diesel heater. Sprinter and ProMaster both have a factory auxiliary port; the Espar AS3 D2L full kit is the default.
- Gasoline van → gasoline heater. ProMaster and Transit both tap the factory auxiliary port with the push-lock fitting in our Webasto kits. Diesel Transit owners: no kit exists here, and that is a fact about the vehicle, not the heater.
- Size it to the envelope, not to your anxiety. 2 kW for a 144-class van with real insulation; 4 kW for 170s, EXTs, big glass, poor insulation, or sub-zero living.
Ready to pick? Start at van air heaters, then get the ducting right with Webasto heater parts. And before you spend anything on heat, spend it on insulation — every point of assembly R you add is heat you never have to buy fuel for.
Frequently asked questions
Can I put a diesel heater in a gas van? You can, but you would have to carry diesel separately in a dedicated tank, since there is nothing to tap. In practice that means a jerrycan or an auxiliary tank, extra plumbing, and a second fuel to source. In a gasoline van, buy a gasoline air heater and tap the factory auxiliary port.
Why is there no diesel heater kit for the Ford Transit? A diesel Transit has no usable factory fuel pickup for an auxiliary heater, so the installation requires dropping the fuel tank and fitting an additional pickup pipe and components. We do not offer a Transit diesel kit for that reason. Gasoline Transits use a push-lock fitting on the unused factory auxiliary port and install without a tank drop.
Is a diesel or gasoline van heater better? They are the same technology with different burners. Diesel units have longer burner life, wider parts availability and slightly lower cost; gasoline units avoid diesel's cold-weather gelling and are less prone to sooting. The deciding factor is which fuel is already in your van's tank.
What size air heater does a Sprinter 144 need? A 2 kW unit. A 144 high-roof with roughly 250 sq ft of envelope at an assembly R-value near 5 loses about 2,000 BTU/h at a 40 °F temperature difference, or 2,800–3,000 BTU/h once glazing and air leakage are included. A 2 kW heater makes 7,000 BTU/h at full output and 3,070 BTU/h at minimum, so it modulates comfortably. A 4 kW unit in that van short-cycles.
How much fuel does a van diesel heater use? Roughly 0.04 to 0.07 gallons per hour, so about half a gallon over a twelve-hour night and around four gallons across a hard week of winter use. Webasto quotes up to 22 hours per gallon for the Air Top 2000 STC and up to 16 hours per gallon for the Air Top EVO 40.
How much battery does a van air heater use? Very little. Running draw is 4–27 W, so a full night costs roughly 150–250 Wh including the glow-plug starts. The start-up surge is the part to design for: about 30 A at 12 V for the first minute or two of each start and again during the shutdown purge, so the heater needs its own correctly fused circuit.
Why does my diesel heater smell and smoke on startup? A brief odour and a puff of white smoke at ignition and shutdown is normal as the burner lights and purges. Persistent smoke, soot at the exhaust or repeated flame-out faults usually mean carbon build-up from running at minimum output for long stretches. Run the heater at full output for 20–30 minutes every few weeks to burn the deposits off, and check that the exhaust slopes downward and cannot ingest its own gases.
Do I need a carbon monoxide alarm with a diesel air heater? Yes. These heaters are sealed-combustion and vent outside, so in normal operation nothing enters the cabin, but a cracked exhaust joint or a failed mounting-plate seal changes that. Fit a CO alarm at sleeping level, test it regularly, and replace it at its expiry date.
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