My control panel is giving me a “premature flame detected” error code, which according to online sources necessitates either cleaning or replacing the flame sensor. Cleaning it seems reasonable before replacing. Has anyone encountered this code and cleared it by cleaning the flame sensor? Any easy way to do so? The manual states a fairly involved dismantle, which I’d prefer to avoid if just cleaning the sensor can be easily done without dismantling the Webasto.
How to Clean Webasto flame sensor Air Top 3500
- Thread starter skunther
- Start date
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,278
Webasto heaters are sold and I believe serviced by SureMarine in Ballard WA (across the canal from Seattle downtown).
www.suremarineservice.com
Welcome - Sure Marine Service Inc
Sure Marine had pretty much nothing for me, and I had already dismantled the heater as I figured I could do it myself, which I did. Flame sensor has now been cleaned. However, the burner seems pretty spent - lots of carbon buildup. That’s why I called Sure Marine, who told me parts for the 3500 are not available in the US market. Recommended I look online, which I already had. I found some OEM replacements in the UK (which don’t look quite like mine, not sure if there are different builds for the 3500. Mine doesn’t have a retaining clip, which the UK ones do - Webasto Air Top EVO 3500 EVO 5500 Diesel Heater Burner Cartridge | 1313132A | eBay.), as well as aftermarket Chinese made replacement burners (look more like mine - no retaining clip, similar to mine, but don’t know if those would pose a safety risk if the QC isn’t great on them - Heater Burner Cartridge Replacement Fit for Webasto 3500ST & 5000ST | eBay).Webasto heaters are sold and I believe serviced by SureMarine in Ballard WA (across the canal from Seattle downtown).
Welcome - Sure Marine Service Inc
I also found some replacement mesh screens, which seems to be the only real issue with the existing burner. Has anyone cleaned/replaced a burner and/or the mesh on one? Replacing the mesh seems would be a relatively straight forward fix (carb cleaner on the burner body and insert new filter/mesh), provided it works, but I’m not clear on exactly what I need. One listing I saw includes the “burner mesh” and retaining clip, but also recommends a nebulous “filter mesh”, and I can’t determine what that actually is.
Webasto Thermo Top C E Z P EVO4/5 AT 3500/ST 310S Burner Screen Mesh Pad + Clip • $17.60
WEBASTO THERMO TOP C E Z P EVO4/5 AT 3500/ST 310S Burner Screen Mesh Pad + Clip - $17.60. FOR SALE! We have all kinds of different parts for Webasto Thermo Top series. New Webasto Thermo Top. Suitable for the following Webasto heaters Webasto Thermo Top C Z E P. 1 pcs retaining clip. No rounded...
picclick.com
I’m actually wondering if the burner I already had on the unit was aftermarket as the mesh screen didn’t have a retaining clip in it, which seems to be included in standard Webasto build.
My current dirty burner. No replacement burner I saw has the retaining bar that mine does (the manual shows a different retaining bar that is screwed into the heat exchanger housing, not what I have).
Last edited:
UPDATE: I checked one more time with Sure Marine again regarding getting the right part number for the burner. They told me mine was an early type burner which would be difficult to find, and recommended I replace the entire heater. Seems a shame to toss a pretty functional heater over a mesh screen.
I will buy the aftermarket mesh screen, clean the burner and see if I can get the retaining clip in.
On an aside, I have read running kerosene through the webasto will work wonders in cleaning the burner and combustion chamber. Does anyone have any experience with this? It seems a regular run with kerosene could save a lot of trouble.
I will buy the aftermarket mesh screen, clean the burner and see if I can get the retaining clip in.
On an aside, I have read running kerosene through the webasto will work wonders in cleaning the burner and combustion chamber. Does anyone have any experience with this? It seems a regular run with kerosene could save a lot of trouble.
UPDATE:
I purchased a mesh and felt replacement on Ebay for $15 instead of throwing down $2k for a replacement Webasto. Fit like a charm. However, the error code F04 (premature flame detection) still comes up after cleaning the flame sensor, so I am going to replace the glow plug/flame sensor as cleaning it didn't seem to fix that issue. I found replacement Webasto sensors for $170 (look pretty similar to thermocouples I have purchased for ~$15 in the past), as well as some Chinese knock-offs for ~$20. Has anyone used any of the Chinese knockoffs? They look identical, and I really don't feel like throwing any more money at Webasto. I'm feeling like a milk cow for Webasto at the moment, and not liking it.
Here's the $170 part:
I purchased a mesh and felt replacement on Ebay for $15 instead of throwing down $2k for a replacement Webasto. Fit like a charm. However, the error code F04 (premature flame detection) still comes up after cleaning the flame sensor, so I am going to replace the glow plug/flame sensor as cleaning it didn't seem to fix that issue. I found replacement Webasto sensors for $170 (look pretty similar to thermocouples I have purchased for ~$15 in the past), as well as some Chinese knock-offs for ~$20. Has anyone used any of the Chinese knockoffs? They look identical, and I really don't feel like throwing any more money at Webasto. I'm feeling like a milk cow for Webasto at the moment, and not liking it.
Here's the $170 part:
Last edited:
UPDATE
I finally received the Chinese knockoff flame sensor. Installed it, after I had replaced the coked mesh from the burner (the mesh manufacturer (sourced in Ukraine) told me to be sure to cut and insert the provided piece of felt under the mesh), fired her up. Everything works beautifully. Total cost was somewhere around $25.
I finally received the Chinese knockoff flame sensor. Installed it, after I had replaced the coked mesh from the burner (the mesh manufacturer (sourced in Ukraine) told me to be sure to cut and insert the provided piece of felt under the mesh), fired her up. Everything works beautifully. Total cost was somewhere around $25.
