Water heater exhaust marks

Update this was the problem thank you for the help

this time of the year many TT are winterized, just make sure you have water in the tank before starting up the flame

CloudDriver wrote:
In the picture below the air adjustment for the burner is the item in the center with the slots. Soot means that there is insufficient air to burn all of the fuel. The adjustment is easy - loosen the screw next to the slots and slide the adjuster left and right until you have a nice blue flame with perhaps a little yellow at the tip.

DrewE is correct that the problem may be related to a partial blockage in the burner tube. A few years ago I had a spider build a web inside the burner tube beyond the adjuster.

Thank you!!!! I believe this was the issue. The tube did not line up well and was getting to much air. I adjusted it and now getting a nice blue flame. I cleaned the wall and blew out the tube. I will let it burn for the day and see what i get. But i am pretty sure this was the problem. Once again thank you all for your response.

In the picture below the air adjustment for the burner is the item in the center with the slots. Soot means that there is insufficient air to burn all of the fuel. The adjustment is easy - loosen the screw next to the slots and slide the adjuster left and right until you have a nice blue flame with perhaps a little yellow at the tip.

DrewE is correct that the problem may be related to a partial blockage in the burner tube. A few years ago I had a spider build a web inside the burner tube beyond the adjuster.

I'd say there's something partly blocking the flue or misadjusted in the burner assembly and you're not getting proper complete combustion. Check for debris, insect nests, etc. in the heater, and if it's all clean, check that the flame looks correct (nice and blue). Likely there is at least some soot to be cleaned out, at the very least, since you're getting it on the side of the RV.

As it's producing soot like this, it's not operating any too efficiently and quite possibly also producing much more carbon monoxide than it should. At any rate, it ought to be a pretty simple and straightforward thing to fix (or have fixed).