Beckwoods M-1000 problems

[Woodburner84]

This was installed in 1984 when home was built. Used every winter, has worked great. Chimney is swept every year. Ashes are tended regularly. Problem is that lately, cannot open doors without smoke boiling out. Damper is in open position, but smoke is coming out into the room. Flu appears to be open with mirror inspection. Any suggestions?

 

[Woodburner84]

This was installed in 1984 when home was built. Used every winter, has worked great. Chimney is swept every year. Ashes are tended regularly. Problem is that lately, cannot open doors without smoke boiling out. Damper is in open position, but smoke is coming out into the room. Flu appears to be open with mirror inspection. Any suggestions?

Sorry, BECKWOOD M-1000 is the correct brand name. I would appreciate any ideas. Thank you.

 

[kborndale]

Chimney cap screen gunked up?

 

[gthomas785]

In addition to inspecting the full flue path, including the cap, for obstructions, check for any upstairs windows that might be cracked open or other reasons for air to be sucked out of the house. Has anything changed ventilation wise (erv/hrv, air sealing /insulation, dryer, bath fan, range hood)? These can all affect draft.