6" Hole in hearth. What do I need to fill the gap for 3" DuraVent?

[kantonburg]

Well I had the day off today and my local TrueValue had a ton of DuraVent pipe (surprisingly). I have a 3" up and over to my hearth where the previous homeowner has a 6" hole for their woodstove. There is roughly 19" from the inside hole to the outside hole in the chimney.

What can I do to fill the gap between where the pipe from the stove goes in the hearth and meets the chimney liner? There is a ton of cold air that comes through that hole when I pull the 6" stove pipe out and I can't imagine a thimble would insulate that well. Can insulation be used? I doubt it, but I'm throwing stones here. Or is there some sort of reducer they make for this?

Here are a few pics to semi-illustrate.

Click for bigger size

Just a basic pic of the hole.



This is the depth from the opening in the chimney to the inside

 

[imacman]

I don't know what kind of pipe you have from the previous owner's woodstove install, but DuraVent has a 6" to 3" reducer. I used a 4" to 8" one on my install to a previous woodstove flue (although mine goes straight up).

I guess it depends on what brand pipe you have now. I took a piece of the old pipe to the dealer, and he matched it up for me.

Here's how mine came out (you can see the adapter at the top):

Edit: BTW, I saw that Tractor Supply had stove pipe on sale this week (30% off??)

 

[hossthehermit]

Based on myexperience with going into a masonry chimney with Duravent, if you get a 6" to 3" reducer , your going to get a reducer with about 7" outside diameter. I bought a 4" to 8" and it was 9 1/2" outside. These are made for going into a Metal chimney. I took a piece of my 4" vent to a local sheet metal place, told them I wanted a piece to fit outside it and into an 8" hole. $50, after I'd paid $80 for the adapter I couldn't use.

 

[imacman]

The 4" to 8" adapter I used also required a "finishing collar", and then a "chimney adapter". The finishing collar locks onto the existing stove pipe, then the chimney adapter snaps into that, and then snap the 4" to 8" onto that.
Seal all that up with Hi Temp silicone, and Voila!

 

[kantonburg]

Based on myexperience with going into a masonry chimney with Duravent, if you get a 6" to 3" reducer , your going to get a reducer with about 7" outside diameter. I bought a 4" to 8" and it was 9 1/2" outside. These are made for going into a Metal chimney. I took a piece of my 4" vent to a local sheet metal place, told them I wanted a piece to fit outside it and into an 8" hole. $50, after I'd paid $80 for the adapter I couldn't use.

Thats what I was afraid of. No one had a duravent reducer so I couldn't measure. I'm going to have to do some "researching" More like improvising.

Oh and the local Tractor Supply only had two elbows and a 36" piece. After the 20% discount it was still more expensive than the TrueValue.