Expert: Steve Tavares - 10/5/2009

Question
I have two fireplaces, both have 8" x 8" flues. I have just had the insides re-done so we can have wood burning fires and I'm having problems with smoke roll back into the rooms. I understand this may be related to the size of the opening of the fireplaces as relative to the flue size. One of the openings is 35"W x 26"H and the other is 35" w x 23" H. What is the proper size opening for these flue sizes?

Answer
I suspect that the issue is Negitive air pressure. Please do me a favor and try this. Then let me know what happens.

1) Before starting a fire, open a window in the room for 10 mins.
2) start the fire as normal with the window still open.
3) Close the window.

I think if you try this there should be no more smoke coming in.

Please let me know what happens.