Having problems With my boiler going under pressure

[robash9608]

I built my furance about a year ago and I've been having problems with the firebox going under pressure. I've got a 146 cfm fan mounted on the door. It's a double pass flue design with 6in square tubing as the flue. The chimney is about 6 ft high. Seems like i might have a draft problem, you can look at the top of the chimney and see the smoke puffing and also the smoke discharges back through the blower. I've been burning 1 year seasoned oak firewood. Any thoughts of why this would happen??

 

[leon]

smoke etc.

Is it possible you have a neighbor that does not like your boiler and has loaded your stack with a chimney surprise?

The only other thing I can think of is a huge slug of creoote fell off and is blocking the flue and the fans back pressure is bleeding back through the door.

 

[robash9608]

The flue is clean, thats the first thing that I done to try to solve the problem.

 

[boyland]

get rid of the flue.

if it is not insulated you are getting reverse pressure from the temp drop