If the window does the trick you are in need of more fresh air. It's quite possible the fresh air you have brought in isn't enough, and you need another HRV or more depending on how much air you need.
Originally Posted by Lloyd H
http://www.engineeringtoolbox.com/ai...oom-d_867.html this is pretty good information on air change rates, but you also need to figure if your fresh air that you currently bring into the fireplace is big enough to support your chimney size.
You should also verify that the chimney is built correctly, chimneys are almost never built properly. Building inspectors don't know what they are looking at, and masons don't always know how to build them either.
We are trying to help you, we don't come on these forums just to bash people. Sometimes it come across that way, but try and remember that the forum doesn't convey tone very well.
As one of the "new people here" and having been a Licensed Mechanical person in the state of Michigan since 1975, and my father before me, I want everyone to know that I have found over the years that fireplaces can be strange, does not matter who built or how, some just cause problems. So as an answer. Is the chimney high enough ? Have you tried making it higher as a test? Are you in a valley or on a hill ? Near a lake ? Is there a peak that although far away is still higher than the chimney ? Have you tried to preheat the chimneys with the doors closed first and than opened them after the fire is burning good ? And as it has been said even if there is air, well keep checking, and good luck with your project.
Last edited by David F; 05-28-2013 at 06:04 AM.
Reason: miss spelled word