Webasto Air Top 2000 – How To Install a New Burner Following Carbon Buildup


Webasto Air Top 2000 – How To Install a New Burner Following Carbon Buildup

We often say that our Webasto air heater is one of the best feature we added to our campervan conversion… until it stopped working… Unfortunately, Webasto / Espar are prone to carbon buildup if some parameters are not right. What is carbon buildup (also know as soot, coking, carbon debris)? It’s evil! It takes root in the burner insert and slowly accumulates under the form of hard black/grey ashes:

Webasto Combustion Chamber Carbon Buildup
Nasty Burner Insert


This hard carbon deposit clogs the stainless steel “sponge” found in the burner insert; the role of this sponge is to diffuse the fuel and mix it with air. The hard carbon also builds its way up just outside this sponge, messing up the air flow in the burner and speeding up the carbon debris accumulation.

Webasto New Combustion Chamber
Webasto New Burner Insert. Notice the stainless steel “sponge” behind the holes (click the picture to zoom)

If the Webasto heater can’t start and/or shut down prematurely, it’s probably a symptom of hard carbon buildup. We had these symptoms after only 200 hours of using our Webasto Air Top 2000STC (we have the gasoline model).

Carbon buildup CANNOT be removed/cleaned from the burner insert! Because the stainless-steel sponge is so fine, it’s impossible to remove the carbon from there. An attempt to clean it will give the impression that it solved the issue, but carbon buildup will come back after a short period. This is what TechWebasto told us and we believe it’s true, because our burner insert was cleaned and the symptoms came back after about 75-100 hours…

Well, cleaning the burner insert didn’t work. It looks like we have to replace the burner insert and this is the topic of this article! But first, we would like to eliminate the source of the issue… what causes hard carbon formation in the first place?? We’re no expert, but here is the information we gathered during our saga.


  • Webasto Gasoline models are more prone to carbon buildup than Diesel models! This is counter-intuitive, but this is what we were told by TechWebasto (quote: “because gasoline is less energy-dense than diesel“) AND we found SO MANY people with issues that we believe it’s true.
  •  A rich fuel/air ratio (too much fuel) will lead to carbon buildup. There is less oxygen at higher elevation, so the mix get too rich in fuel. If used frequently at more than 5000 feet, the unit should be adjusted for high-altitude usage (faroutride.com/webasto-espar-high-altitudes/). In fact, we will go ahead and say that the gasoline models should be adjusted for high altitude out-of-the-box, whatever the altitude you will be using the heater.
  • Air flow restriction in the intake/exhaust pipe. The total length of the intake + exhaust pipe should be less than 5 meters. If using an silencer, the length is reduced to 2 meters! Condensation accumulation in the exhaust pipe will also create air flow restriction, so a 3/16” drain hole MUST be drilled at each low point in the exhaust routing (see our Installation Article).
  • Short cycle time. If the Webasto is fired-up, it should be run for no less than 20-30 minutes.
  • Running on LOW for extended period of time and cycling ON/OFF.


Now that we have a better understanding of the carbon buildup causes, here is our plan.



  • Replace the burner insert with a new one (keep reading for more!)
  • Perform the following to reduce the chance of carbon buildup:
    1. Remove the exhaust silencer.
    2. Drill drain holes at low points of the exhaust routing.
    3. Adjust the Webasto heater for high-altitude usage (we would do this even we didn’t plan on going to high altitudes). This is still O.K. to use it at sea level; the downside is that we can lose around 3-4% BTU, but we rather live with it than have carbon buildup again!



  • Run the heater at HIGH for about 10 minutes before turning it off, every time.
  • Don’t let the heater run at LOW for more than a few hours. And NEVER let it cycles ON/OFF. To do so, we use the Timer and Program features of the MultiControl HD (Buy on Amazon). For example, we run the heater at HIGH when we go to bed and set the Timer to turn it off an hour or so later (the time totally depends on the temperature outside). Then we set the heater to start early in the morning using the Program feature. That prevents the heater from running on LOW and cycling all night.


Are we sure these will solve the carbon buildup problem? NO! But we like our heater so much (when it works) that we’re willing to give it a try!



  • October 2017: We performed the mods listed above.
  • March 2018: The Webasto worked fine all winter 🙂
  • February 2019: Still running fine, no issues!



We ordered these from a Webasto dealer (Webasto Dealer Locator):

  • A new burner insert (Part Number 84883A. It’s the same for the ST and the STC model. This part number is for the GASOLINE/PETROL model only!)
  • A new set of gasket (Part Number 82302A. Don’t attempt to re-use the same gasket!)
Webasto How to Install New Combustion Chamber - Material
New Combustion Chamber (burner insert) and New Gaskets



Let’s do this!

First things first, get that faulty Webasto heater out of the van. Since we installed it ourselves, we figured how to remove it: https://faroutride.com/air-heater-installation/

Webasto How to Install New Combustion Chamber - Removal
Get yourself comfortable!


We want to thank our friends Chuck and Sam for hosting at their place during that process, that helped A LOT!! Sam is a young talented photographer about to build and move into a van, make sure to check him out!!



We now remove the plastic outer casing. No tools needed, it’s all clipped-on:



We then use a flat head screwdriver to spread the retaining clip of the fan:



Next, we disconnect all the connectors from the control module:


And we remove the control module. There are 3 screws to remove:

Webasto How to Install New Combustion Chamber-7


The control module can then be removed:

Webasto How to Install New Combustion Chamber-8


Next, we remove the combustion fan module. There are 5 screws to remove:

Webasto How to Install New Combustion Chamber-Combustion Fan Screws


The combustion fan module can now be removed. Discard the gasket:

Webasto How to Install New Combustion Chamber-10


We’re getting close to the burner insert. Remove these 4 screws and the 3 rubber grommets:

Webasto How to Install New Combustion Chamber-Burner Insert Screws


Now, pay attention. The complete combustion chamber assembly wants to come off, but it won’t work because the fuel pipe (which is attached to the burner insert) won’t clear the cutout. You need to separate the burner insert from the rest of the combustion chamber assembly. They are slightly sticked together, use a little bit of force or use a flat head screwdriver to pry them apart. Here is a picture showing how they come apart (the picture was shot later in the process):

Webasto How to Install New Combustion Chamber-9


Note that there is a gasket between the burner insert and the combustion chamber, discard it.


Here is the removed burner insert:

Webasto How to Install New Combustion Chamber-Burner Insert Removed


There is definitely carbon buildup in there:

Webasto How to Install New Combustion Chamber-Carbon Buildup


The flame monitor (gasoline models only!) and the glow pin are still attached to the old burner insert. Remove them and keep them for re-installation in the new burner insert:

Webasto How to Install New Combustion Chamber-Glow Pin


Here is a sneak peek inside:

Webasto How to Install New Combustion Chamber-Cast Block

There is soot in the form of fine black powder. We cleaned it using a toothbrush and White Gas (Camp Fuel). (the manual says to use benzine, but we’re not sure where to find that?!):

Webasto How to Install New Combustion Chamber-Combustion Chamber Cleaned


O.K., it’s time to re-assemble everything using the new burner insert and the new gaskets. Just do everything in the opposite order! Be very careful not to bend the fuel pipe of the new burner insert and be careful to replace the electrical wire at the exact same place they were. Just look at the pictures above as reference.


We’re done with the burner insert replacement!


Next, we adjusted our heater for high-altitude usage to prevent (hopefully) carbon buildup issues in the future. Here is an article we wrote to perform that task:

Webasto / Espar: High Altitudes Usage



We then started the heater and it fired-up like a new! Nice!





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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. We’ve been on the road since then and every day is an opportunity for a new adventure; we’re chasing our dreams and hopefully it inspires others to do the same!




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You might be interested in these articles:

Webasto Air Top 2000 Heater Installation



25 thoughts on “Webasto Air Top 2000 – How To Install a New Burner Following Carbon Buildup”

  1. Hi Antoine and Isabelle –

    You folks are our heros! Thank you for sharing so much detail with the world of van lovers. We just upgraded from a old, minimally converted Sprinter to a “new” used 2015 Sprinter Van that was converted by a enthusiast who did a really nice job. The only item not working well was the Webasco gasoline heater. Your post on this was a great find for us.

    We’ve ordered the replacement parts and are now wondering if we need to remove the whole unit in order to get to the innards that need replaced or if this can be done more simply by accessing the top of the unit under the seat. Any insights would be helpful.

    Thanks and happy new year + travels! Laurie and Dan, Fruita, CO

  2. Hey,

    Thanks so much for all your detailed hard work. I am just about to purchase a burner insert as I have run into the same issue. I was wondering if you got the genuine webasto burner insert or one of the many many others that exist out there for about 1/6th the price. I am struggling to find any reviews of the webasto version or the off brand ones.


  3. Is your heater still going strong a year later? I just pulled my gasoline 2000ST apart after an F-02 error and found an insane amount of carbon built up inside the burner tube and heat exchanger. Hard to tell if the burner itself is really that fouled up but seems worth it to just replace it while I’m in there.

    The dealer I paid to install the heater originally claimed to have adjusted the unit for high altitude (I told them I regularly use it above 8,500 feet) but I got the feeling they didn’t actually do anything. I’ll be following your adjustment method once I reinstall the heater.

    • Still working fine! Didn’t do any maintenance since October 2017 (when we replaced the burner assembly).

      Make sure to run it on HIGH frequently. Also do you have a silencer?

      • I bought an exhaust muffler and intended to install it but won’t now that I’ve read this. You do recommend an intake silencer/filter though? I have been pretty good about running my heater on high regularly. The problem is I live at 7,000 feet, so I might have been doing more harm than good with an unadjusted unit!

        Also, I’m going to run the high altitude adjustment on mine and have a few questions:
        – I have the 2000 ST (as opposed to the STC) — have you heard from others with my unit that have had success following the procedure in your how-to? Looks like it’s just a different wire that needs to be grounded in the case of the ST (the brown one!) but want to make sure it’s not some wildly different procedure.
        – Did you end up having your exhaust gas analyzed for % CO2 after you made the adjustment? And did tech webasto share the document with you containing the suggested levels per elevation?

        • Hi,
          – We are running the intake silencer, it seems fine (not much air restriction, provides some kind of air filter).
          – Yep, the procedure is the same ST vs STC (like you mentioned, maybe just a different wire to ground?). We haven’t analyzed our %CO2 and I don’t know the exact level to aim for.


  4. How long did it take you to do all this? TO remove the heater, strip it down to replace the burner and then put it all back together.

    Let me know

  5. I had to replace my burner, after reinstalling it in my van. It blows air for a minute shuts off and gives me an error code H0a. Any chance you know what might be wrong? Did yours require any thing else when you reinstalled it?

    • Didn’t require anything else, it just worked after we replaced the burner. Never heard of a “H” code; it’s normally “F” something… Googled it and couldn’t find anything. Sorry I have no clue 🙁

  6. How did you find dealing with Webasto customer service when repairing the heater? Where they willing to assist with troubleshooting? I have heard the Espar customer service and distribution network is superior in North America

    • It totally depends on which dealer your are visiting I would say! I heard good & bad stories…
      Techwebasto.com were willing to help us by email.

  7. I see that you’re in Golden which is where we play a lot. Has your heater been running without issues there overnight? Any false starts or is the issue completely gone? I know you replaced the plate, adjusted to high altitude, repositioned the exhaust and drilled a hole in the exhaust. Am i missing anything to what fixed your problem?

    • Hi!
      It seems our issues are completely gone (fingers crossed); no false start or anything.
      You’re correct about the things we changed. We are also trying not to let it run on “low” for long period of time and we run it on “high” for 10 minutes each time we turn it off.

      We should be in Golden for the next few days, then moving on to Rogers Pass, Revelstoke, Nelson and the area. We love it here even if it’s soooo cold right now! Are you around?

  8. Thanks for all your info, I’m planning on installing a Gasoline 2000 ST soon. Benzine is German for Gasoline, so maybe it’s just a translation thing? Looks like it worked either way. I live at 6,000 feet, so I was particularly interested in your info about high altitude. I guess I’ll skip the muffler.

  9. “Benzine” is just gasoline (I believe) and white gas is just gasoline without the additives – so you made a very good choice.

    Propane/LPG heaters are simpler and less prone to issues – if you are going to an additional tank then it would be worth considering it instead of diesel – there are even “transparent” tanks now which allow viewing of the fuel level.

  10. Hey guys, I know it hasn’t been that long since you made these changes but I’m wondering if you have a quick update? I’m about to pull the trigger on a heater (after doing tons of research) and we’re very curious how the Webasto is treating you now.

    Finding an appropriately sized gas heater is tough. Espar doesn’t have a good solution imo, since the B4 is too big and the B1LC seems outdated. I like the idea of gas over propane for a few reasons. I recently heard that the STC model will replace the ST (even in the US) so I might go that route anyways. It is a lot cheaper. Given the price and the thorough guide you’ve posted I’m really leaning to doing this install as well (with your lessons learned).

    Thanks so much!

    • Hey John,
      It’s only been about 40-60 hours running time since we “fixed” the Webasto, so we cannot draw any conclusion. So far so good (it’s still starts and runs well), but time will tell.

      If issues come back, we will probably install a DIESEL Air-Top with an diesel aux. tank. The diesel models are less finicky, so I’ve heard. I don’t like the idea of having to fill a separate diesel tank, but there are not many other options…

      Let me know what is your final conclusion!!

      • Hey Antoine, thanks for the quick repsonse! I’ve definitely considered going with a Espar D2 and a separate tank. I suppose the Webasto diesel is another alternative. I’ll let you know what we decide to do.

        Cheers, John


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