Black soot on the outside wall

Old 11-23-08, 07:05 PM
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Question Black soot on the outside wall

After a long history with servicemen for my furnace, and a long list of problems, when the furnace started to fail to ignite I decided to clean it myself. After cleaning, within a week I noticed deposits of black soot on the outside wall next to the direct vent outlet. I know that this means an improper combustion but I don't really know how to fix it. For now I increased the air flow ....

I'm thinking that I might've damaged the nozzle when I cleaned it, or didn't place the sparking rods at the proper distance ... or maybe the burner was set to burn "rich" in different atmospheric conditions (it was "serviced" in spring) and now after cleaning it the flow of oil increased ....

I also mention that the furnace functions in very short cycles (2-3 mins up to 10 mins - function of outside temperatures). The last serviceman proposed to replace the burner with a smaller one (Isn't it possible to just replace the nozzle with a smaller one, ajust the pressure, ajust the air, etc.?)

Does anyone have an idea of how to deal with this? Or how to ameliorate the situation until I find a suitable serviceman that will do all the necessary measurements?

Thank you ...
Old 11-24-08, 04:24 PM
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You should never try to clean a nozzle. Replace it.
Without instruments, any changes you make are a guess.
Burners can only be downfired to a certain point before you have to make changes other than just adjustments. Depending upon the make & model of your burner, you could already be at it's minimum firing rate.

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