Poor drafting

QuestionEdit

The fireplace in our home has an annoying amount of smoke that lufts out of the firebox during all fires. This happens regardless of size of fire, location of fire in the fire box, or exterior weather condition.

It is a masonry fireplace 42" x 24"...24" deep...raised 12" off finish floor...built in 76'. It has a clean out box on the exterior and we had a chimney sweep clean it before we moved into the home. It is located on the first floor of a 2 story "slab on grade" home.

The return air is located in the same room about 20' away and the FAU is located in the attic space above this room. Would louvering this return air and shutting it down during fires help balance air pressure? I have checked the flappers of the other vents and can also control air flow to these areas with shutting doors.

I am also wondering if adding a raised hearth to the front of the fire box would improve this situation?

for your help!!

AnswerEdit

first find out what the problem is, open 2 windows in the room with the fireplace and light a piece of incense and if the smoke goes up then you can start fixing the negative pressure of the house if not it might be the construction it self. If it goes up, the house needs make up air or you must stop the air from getting out of the house (attic doors, kitchen/bath exhaust fans, cloths dryers, Radon systems, furnace returns all pull air out of the house, fix this or open a window to get your fire started (trial and error) I would have a local Certified Chimney Sweep www.csia.org, (there you can look up by zip code to find one near you) take a first hand look at what you have they should be able to help.