Smoke Crossover - Need a liner?

[iammarrk]

I have a fireplace on 1st floor (13x13 flue) and an Avalon 990 wood stove in the basement (6" pipe into 9x13 flue). They share a common chimney. When I use the fireplace I get some smoke entry into the basement. After researching and reading I decided that I would benefit from a flue extender on the fireplace flue. I had a company come out and they said that just a flue extender would not help and I also need to add a liner to the basement flue. Trying to figure out if this is just an upsell or if I really do need a liner.

 

[begreen]

Two separate issues. Extending the fireplace chimney should stop the back-siphoning of smoke to the stove. The other issue is one of safety. The Avalon requires a 6" flue of ~28 sq in area. The flue liner is oversized, by almost 4x the requirement. That severely dilutes draft and cools down the smoke in the flue. This can be a recipe for creosote buildup.

 

[bholler]

I have a fireplace on 1st floor (13x13 flue) and an Avalon 990 wood stove in the basement (6" pipe into 9x13 flue). They share a common chimney. When I use the fireplace I get some smoke entry into the basement. After researching and reading I decided that I would benefit from a flue extender on the fireplace flue. I had a company come out and they said that just a flue extender would not help and I also need to add a liner to the basement flue. Trying to figure out if this is just an upsell or if I really do need a liner.

It is possible that you have internal crossover because of a failed liner. But it's unlikely

 

[iammarrk]

No crossover as far as I know. Both flues were inspected. I understand the creosote issue due to low temperatures, but I only use the stove a dozen times a year for ambiance.