Two Flues, One Chimney

[KDubU]

So the house we bought has a new oil furnace installed last year by the previous owner. It is vented up an exterior brick chimney and I did not know this and rather thought it was a direct vent. So currently there are two flues in the chimney, one for the furnace and the other for a propane fireplace that is being removed as well as it’s flue. I guess now I have to see whether both the furnace flue that appears to be 3-4” will allow for a 6” flue for the wood stove to be fitted. I think most of the chimney will have enough room and was planning to get a chimney sweep in but not sure how I am going to get a blocker plate to work now.

Has anyone dealt with this type of scenario? Attached are pics of them outside of the chimney.

 

[bholler]

So the house we bought has a new oil furnace installed last year by the previous owner. It is vented up an exterior brick chimney and I did not know this and rather thought it was a direct vent. So currently there are two flues in the chimney, one for the furnace and the other for a propane fireplace that is being removed as well as it’s flue. I guess now I have to see whether both the furnace flue that appears to be 3-4” will allow for a 6” flue for the wood stove to be fitted. I think most of the chimney will have enough room and was planning to get a chimney sweep in but not sure how I am going to get a blocker plate to work now.

Has anyone dealt with this type of scenario? Attached are pics of them outside of the chimney.

View attachment 309379 View attachment 309380

Yes I deal with chimneys like that every day. As well as mine at home has a double flue. One for the woodstove in the basement (now lined with 6" insulated liner. And one for the fireplace upstairs with a gas insert in it

 

[begreen]

You'll know a lot more once the propane insert is removed. Then the current fireplace flue can be inspected and they can report to you the ID of the chimney flue tile. At that point, the damper area will be visible for inspection and determining the next steps to install an insulated liner and block-off plate.

 

[KDubU]

Tks. From what I can see so far, it appears someone stuffed some insulation (hope it’s Roxul) into the damper area so I will have to remove that to see how much space there is. I know some have to be expanded by removing some brick to get a 6” flue past. Just waiting now for the sweep to come by as the chimney was previously inspected when we bought the house in the fall but not sure how much they could see down the chimney with two flues in there.

 

[bholler]

Tks. From what I can see so far, it appears someone stuffed some insulation (hope it’s Roxul) into the damper area so I will have to remove that to see how much space there is. I know some have to be expanded by removing some brick to get a 6” flue past. Just waiting now for the sweep to come by as the chimney was previously inspected when we bought the house in the fall but not sure how much they could see down the chimney with two flues in there.

Well from the pic I can pretty much see from the efflorescence that the furnace flue offsets to the left just above the fireplace. That also tells me you need a furnace liner as well unless that was done already

 

[KDubU]

Well from the pic I can pretty much see from the efflorescence that the furnace flue offsets to the left just above the fireplace. That also tells me you need a furnace liner as well unless that was done already

Tks @bholler, can you educate or expand on why this occurs? I am assuming you mean the white on the brick?

 

[bholler]

Tks @bholler, can you educate or expand on why this occurs? I am assuming you mean the white on the brick?

Yes the white is what I am referring to. It is caused by moisture condensing in the flue and leaking out through it and then the brick. It brings salts along with it