Webasto 2000STC heater and soot

[donlillegard]

I have a new Webasto forced air diesel heater Air Top 2000STC. I had the predecessor for 10 yrs and loved it. However, the new one puts out an unbelievable amount of soot compared to old one. Sure Marine looked at it and claims it is running "normally" but it is not normal compared to my old one?? Anyone else run into this issue? Perhaps there will be a recall on these in the near future???

[Pete7]

Have you tried a different fuel supply? That or strip it down and give it a clean.

They have been making these things for decades, can't see there being a recall for something that works well for most customers.

Pete

[tkeithlu]

Soot is partially burned fuel. For an unknown reason, the heater is feeding too much fuel for the available air. The cause could be the air supply being restricted/too weak, or could be the fuel feed being too rich. A first step would reasonably be to explore these possibilities, particularly given a unit that serves so many people so well. You might find the problem without recourse to the company.

[Lepke]

Soot is a sign of not enough air in the combustion process. Either the incoming air is restricted or the exhaust is restricted and the back pressure prevents enough incoming air.
If you're drawing air from inside the boat, make sure there is a path for replacement air. Also if your exhaust line is too long or has too many bends can cause a restriction. You may need a larger tube size.

One check is to disconnect the incoming air tube at the unit, see if no restriction solves the problem. Also try removing the muffler.

If you have an additional fuel pump delivering fuel to the metering pump, the pressure may be too high and overpowering the metering pump. A fuel pressure regulator like the one shown is adjustable from 1-5 psi. On Amazon for about $25.
And as a last resort, a higher grade fuel burns cleaner, like #1 diesel or kerosene.

[pdxsailordiver]

After I installed my Airtop 3500.
I called Webasto service(very helpful )and ask how to get long trouble free life from it.
1) only run it on kerosene
2) only run it on high.
3) run it once a month.
I installed a household 7 day programmable thermostat and left the variable webasto stat on high.
8 years later it has been trouble free.

[GordMay]

Is yours a Diesel or Gasoline [or other fuel] model?
For any liquid fueled heater to function correctly, it needs a specific mix of fuel and oxygen [as has been noted].

If running ‘rich’, with too much fuel, and too little oxygen, the heater cannot burn fuel as quickly as it’s being pumped into the combustion chamber, resilting in carbon & soot [unburned fuel].

If the thermostat is short cycling, the heater might only run for a few minutes at a time, and never get fully up to temperature, causeing Carbon to build up faster, since the heater isn’t able to get hot enough to burn it off.
You can avoid this short cycling by seting the heater to max heat, and running it until the boat is warm (at least 15 minutes). Then turn the heater off manually, and allow the boat to cool off on it’s own. Then turn the heater back on manually. Rinse & repeat - I know, it’s a pain in the a#%.

Unfortunately, cleaning all of the carbon from the burner element [an expensive compressed disc of steel wool*], is also a pain. In order to remove the carbon buildup, the heater has to be removed and completely taken apart.

* ➥ https://faroutride.com/webasto-install-new-burner/