Webasto Gasoline Heater Alternatives: Air Top 2000 STC vs Espar S3 vs Apollo G1

Webasto's gasoline heater, the Air Top 2000 STC, sells for about $1,299 as a basic kit and is rated to 5,000 ft (1,500 m). The Espar Airtronic S3 B2L costs $1,499 and up, and it adjusts for altitude on its own up to 13,123 ft (4,000 m). A gas van owner shopping for heat usually ends up choosing between those two. There aren't many other gasoline options.

This page puts both German heaters next to the Apollo G1, the $699.99 gasoline air heater we sell. We've included the things the G1 does worse. The owner problems below are taken from van forums, Reddit threads and retailer reviews.

What a Webasto gasoline heater really costs

Plan on $1,300–$1,800 for the heater kit, plus parts, plus installation if you don't do it yourself. Heatso lists the Air Top 2000 STC gasoline kit at $1,299. Espar's S3 B2L is $1,499 as a universal kit and $1,699–$1,799 for the ProMaster and Sprinter kits.

The kit price isn't the whole bill. For the Espar, Converted Van Co quotes around $720 for installation, and that assumes an empty van. A finished build costs more because panels have to come out. The North American Webasto kit from Heatso does include a fuel standpipe and filter, so you won't be buying those separately.

Some buyers go looking for gray-market Webasto units to save money. Vanlife Outfitters tried one imported for the Russian market, at around $560. The serial sticker said it carried no US warranty. The box was also missing about $90 of parts that North American kits include: a fuel filter, the mounting plate, the floor gasket and the quieter all-rubber pump bracket.

• Webasto STC gasoline: $1,299 kit (standpipe included) + install
• Espar S3 B2L: $1,499–$1,799 kit + install (about $720 professional)
• Apollo G1: $699.99 kit (standpipe and fuel filter included), free shipping, + install

Specs side by side

All three are 2 kW (about 6,800 BTU/hr) gasoline air heaters, so heat output is a tie. The differences are in altitude, fuel use, certification, warranty and who can service them.

Webasto and Espar figures come from Heatso, Curious Campervans and other retailer listings in September 2026. Prices move, so check before you buy.

The altitude problem with the Air Top 2000 STC

The STC gasoline version is built for low elevations, and owners who camp in the mountains are the ones who report trouble. Heatso lists its maximum operating altitude as 5,000 ft (1,500 m). Vanlife Outfitters describes it as designed to work best up to about 4,900 ft.

Above that, thin air throws off the fuel-to-air mix. The burner runs rich and soot builds up fast. One Reddit owner described theirs as starting "acting up over 1500m" and clogging with soot "after a few hours" at 2,200 m. A Heatso reviewer ran one at altitude for about a week before carbon killed it. The repair quote was over $700.

Webasto's answer is the Altitude Adjusted STC, pre-set at the factory to run up to 6,400 ft. Many owners go further and switch on the controller's high-altitude mode permanently, even at sea level. Vanlife Outfitters, a Webasto dealer, now says Webasto doesn't recommend that, because doing it properly takes a CO2 meter and training. Done wrong, it can make carbon worse. Published limits also vary between 1,500 m and 2,200 m, so check the label on your unit.

The Espar S3 B2L gets around the adjustment problem with a built-in altitude sensor. It adapts on its own up to 13,123 ft. It still needs the carbon habits in the next section, but if you spend your winters above 10,000 ft, this is the strongest reason to pay for the Espar.

The Apollo G1 also adjusts its air-fuel mix automatically and is rated to 11,483 ft (3,500 m). That is a design rating. We don't yet have published field data for the gasoline G1 at those heights. Above 6,000 ft, the G1 manual asks for two habits. Run it on the upper heat levels (L7–L9), and give it a full-power burn at the end of each trip.

Carbon buildup: what owners learned the hard way

The most common way a gasoline heater fails is carbon buildup from long hours on a low setting. This is true of the Webasto, the Espar and the G1. Gasoline only burns clean inside a narrow air-fuel window, and a burner idling at minimum output spends a lot of time outside it.

The symptom is familiar to anyone who has read the van forums. The heater starts, shuts itself off, then fails to light with an error. A Reddit owner with a Webasto STC gasoline kept getting a no-flame error code after four months of full-time use. Black smoke was coming out of the exhaust. On the Van Living Forum, one owner had only ever run theirs on low. On the first start of the season it shut itself down, then puffed black smoke on the retry.

What got those heaters running again:

• Run it hot on purpose. The top advice in that Reddit thread was full heat for 30 minutes to an hour, about once a week. After time at altitude, Vanlife Outfitters suggests running at full load for at least a few hours back down low.
• Run it in the off-season too. Vanlife Outfitters tells Webasto owners to run the heater at full load for at least 20 minutes every month, summer included. That keeps fuel moving through the pump and lines.
• Try compressed air before a teardown. That same owner blew the heater out with a compressor and had it running again the same day. The fault came back later, though, and gaskets and parts were two weeks away. Compressed air buys you time. It isn't a repair.
• Let it finish shutting down. The heater stops fuel first and keeps the fan running to cool the burner. Installers warn that cutting power mid-cycle leaves unburned fuel behind to carbonize.

The G1 is no exception. Our manual asks for the same routine: 30–60 minutes at L9 at the end of each trip.

The G1 kit also includes an exhaust muffler, and we recommend leaving it off. A muffler adds back-pressure, and back-pressure speeds up carbon on a gasoline burner. If you fit it anyway for a quieter exhaust, plan on more frequent burn-offs. Our gasoline RV heater buyer's guide explains why gasoline carbons up faster than diesel.

Where the Apollo G1 falls short

The G1 costs about half as much as the German heaters, and you give up six things for that.

1. No E-mark. Webasto and Espar both hold ECE R122 type approval, the European standard for fuel-burning vehicle heaters. The G1 has no R122 approval. It is CE marked under the EMC and low-voltage directives and RoHS compliant. If a fleet spec, an insurer or a European registration asks for R122, the G1 won't qualify.
2. No local dealer. Both German brands have dealers and installers across North America. With the G1 you deal with us by email, and parts ship directly from us. Orders go out within 3 days and usually arrive in 7–12 days, which is a long wait in a cold snap.
3. More fuel at full power. At maximum output the G1 draws 0.30 L/h, against 0.24 L/h for the STC. Over an 8-hour night at full heat, that's about 0.5 L (0.13 gal) more. Most nights you won't be at full heat, so the real gap is smaller.
4. Universal kit only. There's no ProMaster- or Transit-specific G1 kit. The box includes a universal fuel standpipe and a fuel filter. If you'd rather tap your van's auxiliary fuel port, you source that adapter yourself.
5. Shorter track record. The G1 is newer to the US market. There are far fewer owner reports on it, especially above 10,000 ft, than on the Espar S3.
6. Shorter standard warranty. One year, with a 2-year plan available at extra cost. Webasto's is two years.

One thing works in the G1's favor on the electrical side. It pulls about 5.5 A while the glow plug lights, against roughly 10 A for the STC, which is easier on long wiring runs and small house batteries.

Which gasoline heater fits your van

Choose by where you camp and who will fix it. In a Reddit thread on budget heaters versus Webasto and Espar, a gas-van owner asked, "is there a thousand dollar difference between them?" The answer depends on your van and how you'll use it.

• Buy the Espar S3 B2L if you regularly winter-camp above 10,000 ft, want a local shop to install and service it, and can spend around $1,500 or more.
• Buy the Webasto STC if you mostly stay below 5,000 ft (or 6,400 ft with the altitude-adjusted version) and have a Webasto dealer nearby. It also makes sense if your van already has one plumbed in.
• Buy the Apollo G1 gasoline air heater if you want a heater that runs off your van's own tank, you're comfortable installing it yourself, and you'd rather spend about $700 than $1,500. You also need to be fine with email support and a one-year standard warranty.
• Consider a diesel heater with its own small tank if a second fuel doesn't bother you. It was the most common answer in a 119-comment Reddit thread from a gas-van owner stuck with a diesel Webasto. Our diesel heater guide for campers covers sizing and tank setup.

Installing any of the three in a gas van

In gas vans, most install trouble starts at the fuel pickup. These points come from installers and owners, and they apply to all three heaters.

Don't trust the Transit auxiliary fuel port as-is

FarOutRide found the Ford Transit's auxiliary port has a 6 mm inner diameter. Espar and Webasto recommend 2 mm. Their heater lost its prime after about 24 hours and had early carbon problems. A Transit owner on Reddit reported the same prime loss. FarOutRide's advice is to use the standpipe supplied by the heater maker instead. The ProMaster has a usable auxiliary pickup under the cab floor panel. Sprinter kits often need a Dorman connector bought separately.

Mount the pump low and close to the tank

These dosing pumps push better than they pull, so mount the pump close to the tank. For the G1, mount the pump at 15–30° from horizontal. Put the fuel filter on the suction side, between the pickup and the pump, never after it. Prime the line with a syringe before the first start. Vanlife Outfitters advises against sucking gasoline up the line by mouth, having done it once.

Isolate the pump's ticking

Every one of these pumps ticks. A rubber-coated metal bracket bolted to the chassis carries that sound into the van. Hang the pump on an all-rubber mount, away from where you sleep.

Seal the floor and plan the exhaust exit

The gasket under the heater needs to seal fully, or exhaust fumes can find their way into the cabin. Route the exhaust out to the side, away from doors and windows. Fit a carbon monoxide alarm whatever brand you install. Our heater installation safety checklist covers placement and CO alarms.