Too much draft

[Scholl P & H]

I installed a Burnham V83 oil fired beckett boiler. Everything went great until the about a week. The homeowner complained of soot from the damper. Upon evaluation it was found to have a breech of .08-.1 WC causing too much draft. This was causing the flame to pull off the cone creating huge amounts on soot. I called Burnham. They suggested 2 draft regulators and some fine tuning. I consulted a manson who stated the 8x8 18'-20' tall chimney was adequate for a 6" exhaust flue. The boiler also has an encased oil burner, I installed a passive combustion air intake kit with VRV.
What can I do
Help Scholl P&H

[beenthere]

Follow Burnhams recomendation.

[hearthman]

Just a word: I would trust my dentist with sizing a flue before I consulted with a mason. Since 8x8 is the only size they use for heaters, what other size would he offer? Masons have no training or certification in constructing or sizing flues per the codes.

What size nozzle and pump pressure?
Hearthman

[JBM1000]

When there is the right sized flue and gas "wc then there is almost always a positive push from somewhere in the free space the boiler is setting in. Too much make up air etc. "Find IT".