How to seal a fireplace flue

I am now considering putting a stove in front of an existing fireplace and running the pipe into the fireplace chimney. My question is how to best "seal" the bottom of the existing flue vs. having to fill the whole chimney with stove pipe. When I asked Alaska how they would install their Kast Console as an example they suggested that they would use a flexible stainless steel pipe of an ovoid shape and force that past the existing flue damper and stuff fiberglass in around it to seal it.

Thoughts or ideas?

Thanks in advance!

I think Alaska gave you the best answer. Just make sure you go at least 2' above your fireplace damper with your flex pipe.
Jerry

Hello, Thats what I did with the harman elite I put in and it seems to work great. 0 reading on c/o meter and no smoke or smell. I removed the damper door and pushed the oval ss flex tube up 5 ft. stuffed it good with insulation and also put insulation around surround. My very first burn was the other night and it went without a hitch and the burn lasted from 6pm to about 8am with the fire box about half full. What a great way to heat your home! I'm new at this and read everything here before I did the install.

I have a 6" S/S adapter around here some place that I used when I had a woodstove in the fireplace, it is oval too. I think the tube that went up the chimney is about 4' long. It has a flat panel that fits where the damper went and then was sealed in with glass insulation. If I can find it I'll let it go for $75, I think I paid $230 for it new and used it 2 years.

jeromemsn wrote:Hello, Thats what I did with the harman elite I put in and it seems to work great. 0 reading on c/o meter and no smoke or smell. I removed the damper door and pushed the oval ss flex tube up 5 ft. stuffed it good with insulation and also put insulation around surround. My very first burn was the other night and it went without a hitch and the burn lasted from 6pm to about 8am with the fire box about half full. What a great way to heat your home! I'm new at this and read everything here before I did the install.

you don't say wether you you used a plate to cover the damper opening, did you just run the pipe up and stuff regular unfaced insulation around it?

Just stuffed the insulation tight all around the oval pipe works great, and don't forget to put some strips of insulation around the surround also.

That setup will work but it makes it impossible to do any mid season fly ash removal from the pipe unless you can put a"T" in the bottom with a removal cap.

If you dont go all the way up the chimney with flex-tub, one WORD, flyash. think about it.