Oil burner sooting up.

[joea]

Burnham V8. Third soot up in last month. Had run fine for years before this.

After the last sooting, I went through a complete "tune up". Things I did:

The heat exchanger "nipples" (my term) were heavily sooted, so cleaned from top and from sides. Removed the flue pipe, sooty as well and cleaned that too.

Swung the door open and away, cleaned up the soot in there.

Checked pump pressure, seems to hold steady at 140 psi. New nozzle. Fuel seem clean and smells right.

Checked draft, over fire, and in flue pipe.

Got C02 right, I think. Around 10.5 %. Even used new fluid. No smoke visible on paper.

Ran fine for two days. Today, went to check oil level in tank found "a lot of" soot outside of flue damper on burner top and on expansion tank.

Not going to use it till I have an idea of what the heck is happening. This is the THIRD soot up in the last few weeks after running normally for years.

What have I missed here? Why would it run fine, with zero smoke on the test paper, yet begin to soot up in just a few days?

 

[Melensdad]

Is the flue damper working properly.

Sounds like you have everything in the combustion area checked out, but what about exhaust creating back pressure or air intake, if it uses outside air, flowing properly?

 

[joea]

Is the flue damper working properly.

Sounds like you have everything in the combustion area checked out, but what about exhaust creating back pressure or air intake, if it uses outside air, flowing properly?

It has direct fresh air intake with a "vacuum breaker" in the line, which I never see operate. The draft over fire and in the flue were fine.

I don't know how else to check for back pressure.