Webasto/Espar (Diesel or Gas) heater for Van Life: Theory & Installation

Webasto/Espar (Diesel or Gas) heater for Van Life: Theory & Installation

Van Conversion Webasto Air Heater, Final
Photo of author

We’ve been using our gasoline Webasto heater (Air Top 2000 STC) since 2017. It plays a CRITICAL role in our full-time Winter Vanlife snow-chasing adventures (faroutride.com/winter-vanlife) and has kept the van warm in temperatures as low as -31°C (-23F). This article contains everything you need to know to build your knowledge (1- Theory), install the heater in your van (2- Installation), and get a real-world feedback (3- Review). Whether you choose to install different brand (Espar/Webasto), different fuel (diesel/gasoline), or different van (Sprinter/ProMaster/Transit), this should get you going. Follow the guide!


Table Of Content

Disclosure: This post contains affiliate links, which means that if you click a product link and buy anything from the merchant (Amazon, eBay, etc.) we will receive a commission fee. The price you pay remains the same, affiliate link or not.


1- Theory

1.1- In a nutshell

Webasto Espar How It Works Diagram

Gasoline/diesel space heaters generate heat by fuel combustion. The fuel is typically sourced from the vehicle’s main tank, which is very convenient since there is no need to monitor and refill an auxiliary tank. So long as you have gas in the tank, you’ll never run out of heat. Nice! That being said, they also require a little bit of electrical energy to power the fuel pump, the “glow plug” (to ignite fuel during startup), the fan, and the controller. Here is the fuel and electrical power consumption for the Webasto Air Top 2000 STC (7,000 BTU/2 kW):

Fuel Consumption

Current Draw

When looking at the numbers above, keep in mind that the heater doesn't run all day. In cool temperatures (5°C | 40F), you might only need to run it an hour or two in the morning/evening. The colder it gets, the longer it has to run during the day.

Note that you cannot choose between low/medium/high settings; you select the room temperature, and the heater automatically toggles between off/low/med/high to reach or maintain the selected temperature. It’s a bit like a cruise controls on a vehicle: you select the desired speed and the vehicle control how hard the engine works.

One of the major benefits of the Webasto/Espar heaters is that they generate dry heat because they are vented heaters.

Vented Heater

In a vented heater, the air used for the combustion (outside air) is completely isolated from the air used to heat the cabin (inside air). The heat is transferred from one to another via a heat exchanger. As a result:

Vented heater (Webasto, Espar, Propex, etc.)

Non-Vented Heater

In a non-vented heater, the air used for the combustion is the same air used to heat the cabin. As a result:

Non-vented heater (Mr. Buddy and such)

Dry heat is a BIG DEAL because it helps prevent mold issues, which could ruin your van and your health. We have a LOT to say about moisture and condensation management, but that’s out-of-scope of this current article… we highly recommend reading this later though:

Condensation and Moisture in a Van

Why it happens and how to control it

1.2- Choosing the right heater size (BTU)

Both Webasto and Espar offer a 7,000 BTU (2 kW) model or a 13,650 BTU (4 kW) model.

While you might naturally want to go for more BTU (more heat is better, right?), there is a catch: a more powerful heater will run on “LOW” much more often. And when they run on “LOW” for extended periods of time, this type of heater (Webasto/Espar/Planar/Unbranded Amazon Knockoffs/etc.) tend to develop carbon buildup issues (very hard soot deposit) in the combustion chamber and that phenomenon gets worse as you go up in altitude. Too much carbon buildup and the heater will stop working. That being said, you can operate your heater for years without carbon buildup issues by choosing the right size, by following installation requirements, and by operating the heater correctly. To learn more about the issues we had with carbon buildup and how we successfully “fixed it”, scroll down to section: “Carbon Buildup/Sooting Issues“.

We won’t lie, it is difficult to come up with specific guidelines for choosing the right heater size as it involves many variables:

Van Size

A larger van has more square feet to heat, so it requires more BTU.

Insulation Type

The heater must compensate for the heat loss. The more a van allows heat loss (poor insulation), the more the heater has to work.

Carbon Buildup Prevention

Oversizing your heater might sound like a good idea to make sure you get enough heat; unfortunately, this can lead to carbon buildup issues. This variable alone makes our choice much more complicated because getting the right size heater is critical.

Insulated Window Covers

Windows are a MAJOR contributor to heat loss. Having proper insulated window covers is essential for winter vanlife; they minimize heat loss but also make the living area more comfortable (otherwise it's very cold near the windows).


We spent some time in the Arizona desert in winter, and, yes, it gets quite cold at night. We used our heater in the mornings and evenings. On the other hand, we spent an entire winter in Canada (and near the border of Alaska), and that is on a whole different level. It is not unusual to have -30°C (-22F) for days or weeks, day or night. Having a reliable source of heat is critical for safety when it's that cold!

Interior Layout

A van with a "garage" setup like ours requires less BTU, because the garage is not heated as much. And with our living space being in front of the van, having the Webasto installed under the passenger seat is ideal for us. In addition, heat rises, so our "elevated" bedroom area is always nice and warm. On the other hand, installing the heater under the passenger seat might not be ideal for a layout where the living space is in the back.

The combination of all the variables above makes it hard to provide clear guidelines… That being said, after spending two winters full-time in our van in the USA and Canada, here is our opinion on which size heater to get:

7,000 BTU

(2 kW)

Best all-around solution for winter vanlife down to 10F (-12°C). It'll still be enough to maintain your van warm in colder temperatures, but it'll take longer to warm up a completely frozen van (left alone without heating for a long time). That's what we have in our van and it kept us nice, and warm in temperatures as cold as -22F (-31°C) during two full time winter vanlife adventures.

13,650 BTU

(4 kW)

It is worth considering for a van layout without a permanent garage under the bed (which means more space to heat). It is also worth considering (for any van layout) if you expect frequently to be in temperatures below 10F (-12°C) because it has more power to warm up a completely frozen van (left alone without heating) faster.

Again, that’s our opinion, and we don’t pretend that’s the absolute truth. Ask around and you will get all kinds of recommendations. When getting a recommendation from someone else, ask how long they’ve been using their setup, in which conditions, and if they’ve had any issues. Most reviews come from people that just finished their installation and are very excited to share it…  

1.3- What brand/model of heater should I buy?

The two original players in the gasoline/diesel heaters are Webasto and Espar. They both offer high-quality products backed by customer support via a network of dealers (Webasto Dealer Locator | Espar Dealer Locator). If you’ve been following us for a while, you know that we invest in quality components; that’s a philosophy we used for our entire build, and it has paid off. For this reason, we highly recommend one brand or the other.

We now prefer the latest generation of Espar heaters (listed below), because they are pre-wired (greatly simplifying the installation), they feature a built-in automatic altitude adjustment module (nice!), and they come with the EasyStart Pro controller (which has an integrated room temperature sensor). Looks like Espar listened to their customers!



7,000 BTU (2 kW)
Espar AS3-B2L
ItemBuy Link
Ford Transit Kit with EasyStart Pro controllerEsparParts.com
ProMaster Kit with EasyStart Pro controllerEsparParts.com
13,650 BTU (4 kW)
Espar M2-B4L
ItemBuy Link
Ford Transit Kit with EasyStart Pro controllerEsparParts.com
ProMaster Kit with EasyStart Pro controllerEsparParts.com


7,000 BTU (2 kW)
Espar AS3-D2L
ItemBuy Link
Sprinter Kit with EasyStart Pro controllerEsparParts.com
13,650 BTU (4 kW)
Espar M2-D4L
ItemBuy Link
Universal KitEsparParts.com
EasyStart Pro controllerEsparParts.com

*EsparParts.com is an approved Espar distributor located in USA (Michigan), that means you’ll get genuine parts and your warranty will be honored. 

That being said, Webasto is an excellent choice as well and their gasoline heaters are significantly cheaper than Espar at the time of writing these lines:


ItemBuy Link
Webasto Air Top 2000 STC (2kW)Heatso.com
Webast Air Top EVO 40 (4kW)Heatso.com
Webast Air Top EVO 55 (5kW)Heatso.com


Interesting fact: The footprint dimensions (floor cutouts) are all the same for the Webasto Air Top 2000, Espar AS3 or Espar M2; it’s the dimensions of the heater itself that are slightly different:

Webasto Air Top 2000 Dimensions

Dimensions in mm. Click to enlarge.

Espar S2-D2L Dimensions

Dimensions in mm. Click to enlarge.

Espar M2-D4L/B4L Dimensions

Dimensions in mm. Click to enlarge.

1.4- Where to install a Webasto/Espar in a van?

The location of the heater plays a role in heat distribution and hence, your comfort. The ideal placement of your Webasto/Espar depends on your interior layout. 

Forward, under the passenger seat

In most vans (Transit, Sprinter, ProMaster), the passenger seat base has plenty of room for a heater (even if you add a swivel); therefore, it’s the most common place to install a Webasto/Espar. It works great with the “raised bed/garage” interior layout because heat distribution is quite uniform. That’s exactly the setup we have in our van:

Cold air is sucked in from the passenger feet area (that’s the coldest place in the van), warmed up, and then expelled at floor level towards the kitchen. As a result, the floor, the living room (swivel seats area), and the kitchen are nice and warm:

Faroutride Van Interior Swivels

Hot air rises, so the bedroom area is nice and warm as well. Shutting the curtain minimizes the heat transfer between the kitchen and the garage; in other words there’s no need to heat the garage. BUT when it’s very cold outside (like below -15°C), heating the garage is necessary so it doesn’t freeze and to control the relative humidity (prevent condensation). So we open the curtain as needed. Therefore, if you are building a winter van, we don’t recommend completely closing the garage in order to allow some heat transfer.

Faroutride Van Interior (1200px)

Centered or at the back

Another popular layout features a galley that runs through the entire length of the van, with a table that can convert to a bed in the back of the van. With this interior layout, there is more square feet to heat, and the heat distribution is not as uniform. So if the heat source is installed at one extremity (e.g. under the passenger seat), the other extremity might not be comfortable. We would consider installing the heater in the center (with 2 hot outlets apart from each other, maybe?) if we had this layout.

1.5- Installation Requirements

The Webasto/Espar heaters are very sensitive to inadequate installation!

We. really. mean. it. We met many people down the road that initially had issues with their heater (including us); there’s nothing more frustrating than having heater problems in the middle of the night when it’s -30°C outside (true story). We initially developed a strong love/hate relationship with our heater until we tweaked a few things from our installation (and how we operate the Webasto). Since then, we NEVER use our Propex (our backup heat source) as we much prefer the Webasto. We’ve been using our Webasto without any maintenance since October 2017; we love it.

Here is the secret to an adequate installation: READ THE MANUAL. It’s a long, not-user-friendly, confusing read; so take your time and read it multiple times to ensure you fully meet the installation requirements. We’re here to help, and we like to think you can learn from our mistakes, so below is an attempt at summarizing the installation requirements. It is NOT a complete list, so it does NOT replace reading the manual; it’s more like a list of the common mistakes:

Combustion Pipes Length
Combustion Pipes Bending
Exhaust silencer
Exhaust Dumping
Exhaust constant downward slope
Exhaust drain hole(s)
Fuel Pump Location
Fuel Pump Orientation
Webasto Fuel Pump Orientation Petrol Diesel (DP42 pump)
Clamps for fuel line

As we mentioned, this is not an exhaustive list. Please proceed and read the manual! Don’t have time to waste and read a manual? Then you should reconsider installing the heater yourself (or building a van yourself) because requirements are critical for any system to work properly and safely (electrical, plumbing, propane, etc.) 😉 

1.6- Noise Reduction

One of the downsides of the gasoline/diesel heaters is the noise they make:

1- Fuel Pump Clicking (heard outside & inside)
2- Combustion Exhaust Noise (heard outside)
3- Combustion Intake Noise (heard outside)
4- Cabin Fan (heard inside)

1.7- Carbon Buildup/Sooting Issues

Any gasoline/diesel heater (Webasto, Espar, etc.) is subject to producing soot if the combustion conditions are not ideal. The soot can either be a fine powder or a super hard material that deposits on the surface of the combustion chamber (carbon buildup). Too much soot or carbon buildup will eventually clog the heater, and it will stop working.

Air-fuel ratio is critical for a complete combustion reaction. The perfect theoretical air-fuel ratio is referred to as the “stoichiometric combustion reaction” (Google it!), and in this condition all the fuel is burned completely, thus minimizing the rate at which secondary byproduct (soot) is produced. But we don’t live in a perfect theoretical world, so the actual combustion reaction will either be lean (less fuel in the air-fuel mix) or rich (more fuel in the air-fuel mix).

Lean Burn

(lean air-fuel ratio = too much oxygen)

Clean Burn

(adequate air-fuel ratio)

Rich Burn

(rich air-fuel ratio = too much fuel)

So a rich burn is the condition that promotes soot and carbon buildup. Okay, but how can we avoid it? This page contains all the information to prevent it, but here is a recap of the most common causes:




So let’s be real. In most cases, carbon buildup issues could have been prevented.

When we had issues, we immediately sent our heater back saying it was problematic. After inspection, they found no issues with it. How could that be? We re-installed the heater (after it was completely cleaned by the Webasto crew), and the problems came back. It was hard to digest, but we were left with no other choice than thinking we might be responsible for this. So we completely revisited our installation and the way we operate that thing (keep reading!). Because we changed many variables at once, we can’t tell exactly which one solved our issue. But we can tell that our issues are definitely gone because of these changes. We learned the hard way, and hopefully you can learn from us and prevent problems (instead of fixing them)!

If your heater suddenly stops working for no reason or if it doesn’t want to start, there is a pretty good chance that it’s clogged with soot or carbon buildup. There is no specific fault code for that; you’ll get a bunch of different codes. At this point, you most likely have to change your burner assembly (combustion chamber). We did it in the past and we documented it here:

1.8- Effect of altitude (and how to mitigate it)

The concentration of oxygen lowers with altitude. This has a huge effect on combustion engines or anything that burns fuel really. Indeed, the correct air-fuel ratio is critical for the combustion reaction to be complete (to burn all the fuel).

Gas/diesel heaters are designed to work at sea level. At this altitude, the air-fuel ratio is ideal and the heater burns “clean”. But as soon as you go up a hill with your van and gain altitude, the air-fuel ratio starts to change: there is less oxygen and the heater burns “rich” in fuel (as described in section: “Carbon Buildup/Sooting Issues“). If you spend most of your time at lower altitudes, the amount of pollutants generated is small, and the heater should be able to “clean itself” when it runs very hot (HIGH). If you spend most of your time at higher altitudes, the amount of pollutants is such that the heater can’t clean itself, and it will eventually clog with soot/carbon. As a general rule, 1,500m (5,000ft) is considered high altitude and you might have to take action if you spend an extended period (a few days) above that altitude:


Automatic Altitude Adjustment

The following heater models feature an automatic altitude adjustment (no action needed!):

Manual Altitude Adjustment

The following heater models must be adjusted manually:

Webasto Air Top 2000 ST/STC High Altitude Adjustment Procedure

The high-altitude adjustment can be performed by a Webasto dealer; they have access to specialized tools that analyze the exhaust gas to validate that the air-fuel ratio is correct at the altitude where the adjustment is performed. Or you can actually perform the adjustment yourself, like we did. To do so, you will need the rheostat controller:

Webasto Rheostat

1- Connect the CO2 calibration wire with the ground
2- Turn the control knob to 12:00
3- Turn the control knob to 9:00
4- While the heater is still running, disconnect the CO2 calibration wire from the ground
5- Did it actually work?
6- Driving back to sea level
high altitude adjustment is permanent
  • It means that if the Webasto is unplugged, or if the main power is turned off, the high altitude adjustment is not lost.
  • The high altitude adjustment remains until it is manually adjusted back to sea level altitude. 
Adjusting the Webasto Air Top 2000 ST/STC back to sea level altitude
  1. Connect the CO2 calibration wire to ground.
  2. Turn the heater control knob to 9:00. Wait a few minutes.
  3. When the LED on the rheostat begins to flash, turn the control to 12:00, and keep the heater running for 3 minutes.
  4. While the heater is running, remove the CO2 calibration wire from ground.

1.9- How to operate properly

Webasto MultiControl

Heating your van with a Webasto/Espar requires a little bit more proactivity than heating your house. In a house, you simply set the desired temperature, and you can forget about it. With the gasoline/diesel van heater, doing the same might eventually lead to carbon buildup issues in the long run.

True story: when we were initially rookies and naïve, we would set our Webasto to 20°C when in the van and to 5°C when going skiing all day. It didn’t take too long for our heater to clog with soot and completely stop working… (note that we also made little mistakes in our installation, as described in “installation requirements” section above)

Lesson learned: If the heater is left at 5°C all day (to prevent the van from freezing) when it’s not so cold outside (around 0°C and -10°C), the heater might run at LOW for an extended period of time, and it might also cycle (ON/OFF) frequently (depending on the outside temperature). As we now know, this can lead to carbon buildup issues.

Corrective actions: To prevent carbon buildup, we now operate our Webasto Air Top 2000 as follows:

  1. Instead of running it constantly all day/all night, we take advantage of the Multicontrol HD timers, and we run the heater in short bursts. For example, we set a timer so the heater stops an hour after we go to bed, then runs for an hour in the middle of the night, and then starts again an hour before we wake up. This minimizes the cycling and the duration that the heater spends on LOW.
    • Note that the bursts frequency/duration vary a lot with the outside temperature; there is no secret recipe, experience will teach you.
    • Remember that higher elevation makes the carbon buildup problem worse. So at 8,000 feet we would not let the Webasto run at LOW at all, while at sea level we’ll let it run at LOW for a few hours without being concerned.
  2. Before turning the heater OFF, we took the habit of running it at HIGH for about 10 minutes. The idea is to “clean” it before it cools down (in other words, to clean it before soot hardens). Note that we sometime forget and we don’t go crazy with this.
  3. Do not use your heater for less than 15-20 minutes. This is to let the heater reach a high temperature and clean itself.

Conclusion: Operating a gasoline/diesel heater as described above might sound irritating, but for us it is part of the Vanlife; we got used to it. And to be honest, the way we operate it might be a bit over the top… With a proper installation and at sea level, all of that might not be necessary. But we haven’t had any issues since 2017, so maybe it has something to do with the way we operate it?

1.10- Remote Room Temperature Sensor

The temperature sensor of the Webasto/Espar is located in the heater cold air intake, not in the controller (except for the Espar S2/M2 with EasyStart Pro controller)! This is important to know, as many people believe their heater is wayyyy out of adjustment when they first use it. 

Take the case where the heater is installed under the passenger seat: ambient air under the seat is much colder than ambient air in the living space. So setting the temperature of 20°C on the controller is equivalent to setting the temperature to 20°C under the seat; as a result, ambient air in the living space will be much higher than 20°C! It’s not a major issue, but it’s a bit irritating.

Fortunately, there is a way around it. It is possible to install a remote room temperature sensor. Once installed, the heater will use this sensor instead of the built-in sensor at the cold air intake. We personally installed our remote room temperature sensor near the MultiControl HD, approximately at shoulder height in the middle of the living space (further away from the hot air exhaust). This way, choosing 20°C on the controller means the living space will actually be 20°C!

Temperature sensors are best located at shoulder height in a central location:

Webasto, SensorPush (faroutride.com/sensorpush-review) and Simarine (faroutride.com/simarine-pico) temperature sensors:

Remote Room Temperature Sensor for Webasto Air Top 2000 ST/STC
Webasto Room Temperature Sensor (9005004B)
Remote Room Temperature Sensor for Webasto Air Top Evo 40
Webasto Air Top Evo 40 Room Temperature Sensor (9030883A)
Remote Room Temperature Sensor for Espar AirTronics D2/D4/D5
Espar Room Temperature Sensor (251774890300)
EasyStart Pro Controller for (new) Espar S2/M2 models
The controller includes an integrated room temperature sensor. Nice!

1.11- How to activate all timers on the Webasto MultiControl HD

The MultiControl HD is advertised as having 21 timers, and it does. But there is a catch: only one timer can be active, meaning you can’t actually pre-program your heater for multiple ON/OFF cycles. This is due to legal requirements for passenger vehicles.

Fortunately, there is a way to re-program the MultiControl HD to unlock all 21 timers. After this procedure, you will be able to make all of them active simultaneously:

1- Remove the back cover of the MultiControl HD
2- Connect the brown wire to the second tab of the diagnostic access connector
3- Select "Service" menu and choose the number of active timers
Webasto MultiControl HD Activate All Timers-Service Menu
Note: The "Service" menu also has a bunch of other options
  • Change heater
  • Adjust min-max duration
  • Permanent mode
  • Cancel ventilation
  • Temperature range
  • Show room temperature (a cool feature)
  • Unibox set
  • Undervoltage shutdown
  • Unlock heater (careful with that one)
  • Base configuration

Thanks to Marc B. for providing these instructions!

2- Installation

We installed a Webasto Air Top 2000 STC in our Ford Transit van. The procedure will be slightly different if you've got a different van (Sprinter, ProMaster, etc) or a different heater (Espar), of course, but the general principles remain the same.

2.1- Overview

Time Spent

25 hours

We had a lot to figure out at the time, but we hope this guide helps you finish the job faster than us!



Heater Kit of you choiceSee recommended kit in section 1.3: “What Heater Should I Buy”1Section 1.3
Mount Plate*If your kit doesn’t already include one.1Amazon
Ford Transit Auxiliary Fuel Port Kit (per Bulletin Q-228)Part Number: CK4Z-9B210-A (gasoline Transit)1eBay
Part Number: CK4Z-9B210-B (diesel Transit)1eBay
Webasto Fuel Line Reducer (7.5mm to 4.5mm)To connect to the Transit aux. fuel port1vmacs.net
Heat Shield Sleeve 3 feet lengthRadiant Heat Barrier for fuel line1Amazon
3M Undercoating Spray (Rust Proofing)To seal and protect cut/drilled metal against corrosion1Amazon
3M SM600L ThinsulateTo insulate the seat pedestal area (you most likely have leftovers from insulating your van!)1TheSwivelShop

2.2- Install the Webasto/Espar Under The Passenger Seat

2.2.1- Remove the passenger seat

Remove the 2 screws in the front:

Remove the 2 screws in the back:

Disconnect the wiring harness. The seat is free to go!

2.2.2- Remove the jack and trim the bolt

Take the jack out of the way (it can be re-fitted here afterwards). We had to trim on of the jack's bolt to make room for the heater:

2.2.3- Locate where to install the heater

Good to know

Mount Plate

It is critical to install the heater on a flat surface. This way, the gasket (the large rubber thingy under the heater) can seal effectively and prevent fumes (and carbon monoxide) from entering the cabin. Most likely, your van’s floor is not perfectly flat. That’s why using a mount plate is so important.

The heater must be located so it doesn't clash with the seat base (black structure with the bar code sticker in the photo below), but also so the combustion exhaust/intake, the fuel line, and the installation bolts are accessible under the floor... it's more difficult than it looks because space under the floor is VERY tight!

Looking on top:

Van Conversion Webasto Air Heater, aluminum plate
(We made our own mount plate, but it can be purchased. See "Material" section)

Under the floor (this is an "after" photo):

Van Conversion Webasto Air Heater, under the van
(This is an "after" photo)

If we had to start over

As you can see, we drilled a hole for each component (intake, exhaust, fuel line, mount bolts). This makes the installation / removal of the heater a real struggle because it is SO HARD to work from under the van (because of the very tight space). If we had to do it again, we would probably do it like this:

  1. Cut a single “large” cutout in the van’s floor.
  2. Install the heater on the mount plate (exhaust, intake, fuel line and bolts).
  3. Secure the mount plate to the van’s floor and seal it. 

This way, the installation / removal can be performed from ABOVE the floor (instead of under the floor), which makes things MUCH easier!

Good to know

Rust Prevention

Paint adds pretty finish and colors, but it also plays a critical role: paint prevents metal from rusting. When trimming a cutout (e.g. roof fan opening), drilling a hole, or even when screwing a self-tapping screw in the van (we recommend using cross nuts instead), metal is left bare around the edge and eventually initiate rust. The best way to prevent rust is to restore the finish on the bare metal by applying a layer of primer, paint, and clear coat (your local Auto Parts Store can provide this, and they can match your van’s color). Each layer must be allowed to dry, so this is really time consuming… Second best way to prevent rust is to apply a layer of rust proof undercoating (see “Material” section above) on the edges where bare metal is exposed. This is quicker, but not as effective as restoring the finish; it’s definitely better than doing nothing though.

2.3- Install the Combustion Exhaust

Good to know

Installation Requirements

To prevent carbon buildup / sooting issues, follow all the installation requirements from the manual (as reiterated in our “Installation Requirements” section above)

Following all the installation requirements (length, slope, bends, etc.) left us with little choice: our exhaust is routed near the passenger-side rear wheel. People often point out that installing the exhaust near the passenger door can let the gas get inside the van… But in reality, the doors and windows are always closed when we use our heater; remember it’s cold outside 😉 So we don’t get anything inside the van. Using the door to enter/exit is not problematic either.

2.4- Install the Combustion Intake

We made a mud-deflector-3000 from an old plastic bucket, and it’s zip-tied to the van. Then we attached the intake to it. As simple as that:

2.5- Install the Webasto / Espar Fuel Pump and Fuel Line

2.5.1- Fuel Line

We routed the fuel line (and the fuel pump’s electrical wire) under our Ford Transit as follows:

Van Conversion Webasto Air Heater, fuel line routing
Van Conversion Webasto Air Heater, fuel line shield

2.5.2- Fuel Pump

We initially installed the fuel pump using a cross nut and the clamp provided with the Webasto installation kit (not shown in the photo, a small piece of foam as an attempt to dampen the clicking noise):

However, we recently tried to mount the pump with a Quick Fist (amzn.to/39VWWQZ), and the clicking noise reduction is HUGE – to the point where we don’t really hear the pump inside the van anymore. The quick-fist is zip-tied to the tank attachment strap:

Webasto Espar Fuel Pump Quick Fist Clamp Noise Reduction

2.5.3- Tapping into the fuel tank

Heads Up!

The Transit’s auxiliary fuel port inner diameter is 6mm, which is much larger than what Espar & Webasto recommend (2mm). That’s more volume of fuel to pump and as a result the heater may have more difficulty to start (especially at high elevations) and the fuel line may not stay primed. It may also increases risk of carbon buildup.

We used the auxiliary fuel port for years and it worked (and still works), as described below, but we did have some carbon buildup issues at first and we noticed the heater would loose it’s prime after 24 hours or so.

From now on, we recommend using Espar & Webasto provided fuel standpipe instead of the Transit aux. fuel port. This is per Espar of Michigan‘s recommandation, following an investigation they performed on the Transit.

You will have to completely remove the fuel tank, which is a bit more involving. We don’t have the instructions yet because we still haven’t install the heater on our new van, so for now you can refer to the following threads:

The Transit fuel tank features an auxiliary fuel port and pick up straw; no need to drill! That being said, the auxiliary fuel port comes with a plug; you need to purchase and install the aux fuel pump kit (purchase link under “Material” section in this page).

To connect the Webasto fuel line to the Transit aux. fuel port, we initially made our own reducer out of 5/16" and 1/4" rubber fuel line:

HOWEVER, we later found this Webasto reducer and we would recommend it instead (it minimize the formation of bubbles, that's what we have on our van now):

To install the auxiliary fuel port, the tank must be lowered. So first things first, make sure that the fuel tank is almost empty before lowering it.

Remove the 6 bolts securing the tank and lower it. The tank is surprisingly light weight if emptied. No need to unplug anything, but it won't go all the way to the ground, so use about just anything to keep it higher:

This is how it looks after putting it back together. We protected the Webasto fuel line inside a rubber fuel hose, but looking back many years later, it seems that might be unnecessary as we didn't observe any damage from rocks or any flying object.

2.5.4- Fuel Pump Electrical Connection

The fuel pump has no polarity. In other words, it doesn’t matter which wires you connect together.

2.6- Cabin Exhaust (Hot Air Duct)

We used a holesaw (2-3/8") to create a cutout in the seat pedestal (and restored the finish on the bare edge):

We installed the Webasto outlet on the seat pedestal and we used the provided clamps to secure the duct:

2.7- Cabin Intake (Cold Air)

Simply snap the protective screen on the Webasto intake (sorry no photo, but you'll figure it out!).

2.8- Electrical Wiring

Connect the wiring harness to the Webasto. We routed our harness between the seat pedestal and the floor and then in the driver-side wall all the way to our electrical system cabinet.

Connect your controller to the harness (the rheostat is connected to the pigtail labeled as "Potentiometer", or the MultiControl HD to the pigtail labeled as "Telestart"):

Webasto MultiController vs Rheostat

Connect the wiring harness to your 12V distribution (fuse block). Red wire is positive, brown wire is negative. We've got a diagram & tutorial for you if you're still at the stage of figuring things out 😉

2.9- Remote Room Temperature Sensor (Optional)

We mentioned in the “Theory” section that the temperature sensor of the Webasto is located at the cold air intake of the heater. As a result, there is always a mismatch between the temperature obtained in the living space compared to the temperature selected on the MultiControl HD (the living space is warmer than selected). The solution is to install a remote room temperature sensor in the living space (near the controller): once installed, the Webasto heater will use this sensor instead of the one in the cold air intake. Then the living space temperature will match with the one selected on the MultiControl HD! Here is how to install the remote room temperature sensor on the Webasto Air Top 2000 STC:

There is a resistor hidden somewhere in the wiring harness. The goal is to replace the resistor with the remote room temperature sensor instead:


Here is what the resistor looks like (after we trimmed it). Expect it to be hidden in the wiring harness under black tape, so you'll have to search for it:

We found the resistor near the Webasto heater itself. The remote room temperature sensor is 5 meters long, that was more than enough to route it towards the back of the van:

We installed the remote room temperature sensor near the MultiControl HD, and, since then, the temperature of our living space matches with the temperature we select on the MultiControl HD!

2.10- Starting The Webasto for the First Time

You made it! Ready to fire up!

  • Not so fast… we emptied the fuel tank in order to lower it, right? Remember to refill it 😛 On the Ford Transit, the tank must be above 1/3 full or otherwise the pump will only suck air.
  • If you’re doing the installation during summer, you should know that the maximum outside temperature (for combustion air) allowed is 20°C. Above 20°C the heater might not want to start or might automatically shut down.
  • The fuel pump on the Webasto/Espar is self-priming. There is no need to manually fill the fuel line. However, expect around 2 to 4 false starts before the fuel line is primed (before the fuel reaches the Webasto heater). The longer the fuel run between the fuel tank and the Webasto, the longer it takes for priming.
  • A “false start” is when the heater does not detect fire and aborts the startup sequence. It takes about 2 minutes for the abort sequence to kick in. Once it kicks in, the heater stops pumping fuel, and the combustion fan goes full speed to evacuate the excess unburnt gas from the combustion chamber. Let it do its thing. After a false start, the controller flashes to indicate an error; it has to be reset before it can be fired up again.
  • Once it successfully starts, let it run at max power for at least 15 minutes. As you know (you read the “Theory” section, right?), once started, the Webasto/Espar should always be allowed to reach its maximum temperature to keep it clean.

3- Review

3.1- Recap of Events and Issues we had







3.2- What we like / don't like about our Webasto Air Top 2000 STC

3.3- If we had to start over

We’ve been living full time in our van since 2017, and we’ve been through a lot, so it’s fair to say we know what works and what doesn’t work for us. SO, if we had to build another van, what heater would we choose? We would go for a gasoline/diesel heater again over a propane heater. We did have issues at first, but we learned a lot an we’re confident we can get it right the next time.

This page (theory & installation) is UP-TO-DATE with everything we learned along the way. That’s how we would do things next time 🙂

3.4- Related Guides

That’s it, you reached the end… but there’s more! We also prepared the following guides, which are very related to the heater topic:

Want More?


Stay in touch!


About us



Hello! We’re Isabelle and Antoine 🙂 In 2017, we sold our house (and everything in it), quit our engineering careers, and moved into our self-built campervan. Every day is an opportunity for a new adventure... We’re chasing our dreams, and hopefully it inspires others to do the same!

Heads Up: Exclusive Deals!

Thanks to all of you, we managed to negociate group discount on these. Strength in numbers!

113 thoughts on “Webasto/Espar (Diesel or Gas) heater for Van Life: Theory & Installation”

  1. Hi Antoine.

    You ran your electrical line inside across the space between the seats. I was thinking of doing the same. are you able to describe, or share some pictures of what you did?

  2. A helpful article. A micro furnace like Webasto/Espar etc are excellent ways to heat.

    A strong word of advise or caution … Always ensure you have a functional carbon monoxide detector. A fuel burning heater is a source of CO and it operates while you’re sleeping. Make sure you have a CO alarm in case there’s a malfunction or problem that causes CO to enter the van cabin while sleeping. This could save your life!

    • Unfortunately we don’t have a PDF version. You can export this page as PDF with your internet browser (Print -> save as PDF).
      Hope this helps, antoine

  3. When you chose the Air heater did you consider hydronic as an option? I enjoy reading your sections where you talk about different options you evaluated and would be interested in your thoughts on hydronic vs. air gas heaters?

  4. Does the combustion intake need to be outside the vehicle. Looking at drawing combustion air from inside vessel cabin but exhaust out side. Do you see any issue with this? Cheers

    • I wouldn’t do that:
      1- Potential for CO2 poisoning.
      2- Gas smell will most likely enter the cabin.
      3- Loud noise from combustion.
      4- Pressure difference between inside/outside may mess up with the combustion.

      I’m no expert, but I really think it should NOT be done.
      Cheers, antoine

  5. Hallo,
    In my Sprinter van, I have an Airtop 200STC with SmarTemp 2.0 control.
    Is there a way to adjust for altitudes above 1500M?
    Many thanks.

  6. I am on the road now without a heater and was hoping to find someone who could install a heater for me in the next week or so. I’m currently in Tampa but headed towards Atlanta and sc before moving on to Indianapolis where it’s really cold right now. Any suggestions?

  7. Hi Antoine, I have just read your article and watched the Rich Built you tube video. He recommended looking at your details.
    Before I install my Esbar in 2 weeks time, I wondered if I could drop a new rigid 2mm pick up pipe down the Ford Aux 6mm pick up pipe so I wouldn’t have to remove the whole unit from the tank?


    • I had the same question and would love to learn about any results. I had also considered finding some way of reducing the factory pipe and was curious what others came up with. Waiting on delivery of my transit so I’m still working on theory and design so I have no way to get hands on and dig in yet.

  8. Greetings! Thank you for your wonderfully informative site. Readers – make your purchases through this site to support Isabelle and Antoine and the fabulous content they post!

    I’m interested in your thoughts re. Greg and Andrew’s earlier questions, especially related to attaching the mount plate to the van floor:

    “Can you expand on your “If we had to start over” section in which you talk about cutting a large hole for the fuel and intake and exhaust pipes. I don’t understand your comment on “secure the mount plate to the van’s floor and seal it”. Would removal consist of removing the mounting plate and the furnace.? How would the mounting plate be secured to the floor?”

  9. Hello! I have been following your build journal rather religiously. I see that you have the installation of the Webasto listed rather far ahead of the electrical system setup, but then say the electric system is a pre-requisite for the Webasto install. I am a bit confused. Help?

  10. Question….

    I was able to get Multicontrol into service mode but I think it may be stuck there now and quick start button is always lit? Anyone else run into this?

  11. Just to be clear. Do you use plus nuts in the floor of the van to mount the mounting plate to, so that you can remove the heater along with the air exhaust, supply and fuel lines, from above?

      • Hi Antoine. Sorry to bother such a quiet board. And I couldnt find how to start a new message with you, so I am replying to maybe a relevent question.

        I am curious if you feel that ethanol fuel gives you any issues with the heater. I have a gas E-350, and I am debating to get a gas powered air heater and tie it to my tank, which is often filled up with 10% max ethanol, or if I should opt for a diesel and get a small gallon (or smaller) tank to keep inside the van (similar to what you see on all the cheap China heaters).

  12. To solve your un-priming issue below 1/3 tank and to resolve high altitude start issues caused by low vapor pressure of gasoline install a 2mm pickup straw in your tank instead of the 6mm factory auxiliary fuel straw. A straw can be fit through the cap of the fuel level sending unit without having to drill the tank. This solves all Espar un-priming and high altitude start issues. You can also put the straw lower in the tank if you wish to be able to run the tank to lower fuel levels.

    • I don’t know this but I did trade gasoline for a bit of my career and I think the ethanol in the fuel is part of the issue. Which doesn’t change based on octane rating. Ethanol tends to gum up smaller engines like lawn mowers, weed eaters, etc. so it could be causing some of the same issues here. Having said that, I would think a higher octane rated gasoline could help alleviate some of the issues too.


Leave a Comment