Fireplace draft issue

[tborgers]

Hi all,

I have a fireplace and sometimes I get smoke pushing back into the house. From the top of the chimney, There are two holes going downward. My furnace uses a seperate exhaust and so does my water heater. The only thing currently connected to my chimney is the fireplace. I get smoke pushing back and I cant see where the other hole from the chimney ends. I only see one chimney hole if Im looking up from the fireplace. Please Help. Where does the second hole in the chimney go?

Thanks

 

[Grisu]

Why do you think having a second flue in the chimney is somehow contributing to your smoke problem? Right now I don't see how those two things are connected to each other.

At what part of the burn do you get the smoke spillage into the room? How airtight is your house? Has opening a window reduced the amount of smoke backdrafting? Are there a lot of other appliances that draw air from the house (range hood, bathroom fan etc.)? And what are the dimensions of the fireplace, flue and the chimney?

 

[tborgers]

I'm not sure if the second flue was for supply air to the fireplace maybe because I cant see where it even ends, only where it starts at the top of the chimney? The spillage starts from the beginning all the way to the end of the burn. Opening a window helps the draft a lot. The front of the fireplace opening is roughly 20" wide and 12-14" deep. The flue is 6" and goes directly up with zero bends. The chimney flue is not plugged at all and is clean. There is a bathroom fan and Range hood but neither are on during the burn.

 

[tborgers]

And the house is really airtight with new windows and doors.

 

[Grisu]

Can you post a pic? Is that a prefab ZC fireplace? Or maybe a coal-burning fireplace.

 

[tborgers]

Im not at home to take a picture, but i can later today. The house is 40 years old, so I dont think it would be coal?

 

[tborgers]

the wood sits right on the stone base, with the exception of a metal cradle/grate.

 

[bholler]

you said your house is really tight that is very lickley the problem open fire places need massive amounts of air to draft properly. Also what is the opening size and the size of the flue?

 

[Sprinter]

Opening a window helps the draft a lot.

So there's the problem. Like bholler said, open fireplaces suck a lot of air. If the house is too tight, it just can't breathe. Stoves are bad enough sometimes and often need outside combustion air.

Is this house new to you, or have you been able to burn the fireplace in the past without problems?

 

[jdp1152]

40year old home.... It's not likely it's because it's too tight unless you've done a lot more than change doors and windows. Stack effect/negative pressure is more likely the culprit. Had this issue with my fireplace and eventually with my insert. Spent a lot of effort on air sealing the building envelope starting attic down. The only smoke spillage I get now is when I do a cold start and don't warm the flue up. Amazing how leaky an older home can be.