Chimney Support Box Issues- help!

Hi all!

I have been having issues with controlling the draft/airflow in my Avalon Pendleton due to my chimney support box not having a stove pipe adapter, resulting in significant air gaps between the side of the stove pipe shoved into the hole & the edge of the box (crude rendition of set up made in MS Paint attached, will try to get actual pics later). It is labeled as an Amerivent 6 FB-CS.

Is there an easy way to either add a stove pipe adapter to it or replace the support box without having to replace the entire ~16 feet of Class-A chimney pipe above it?

I've consulted with both our local wood stove installer & our local chimney sweep, and they both say their insurance won't let them work on any part of the wood stove-chimney system with out replacing the entire Class A chimney due to the fact that no one knows when the chimney pipe was installed (the house was built in the late 1940's & we estimated the previous stove that was in there before the Avalon was likely installed not that long after (maybe 50's or 60's???) based on the set-up)

they both said the condition of the chimney seems just fine. The way the pipe goes into the support box is the only issue either of them had with the set up (actually I take that back, the sweep said I should put a slip joint in somewhere on the stove pipe so it's easier to remove to vacuum out the soot after sweeping)

begreen said:

It probably should all be replaced, especially if that old. What did the installer and sweep say about the condition of the current chimney pipe? My guess is that it is underrated by today's class A requirements. The FB series today is rated at 1700º instead of their HS class A pipe with a requirement of 2100º. FB is not rated for solid-fuel appliances. You could give Amerivent tech support a call to verify.

Click to expand...

just looked on their website where they describe a 10fb model as "engineered for venting all gas or liquid-fueled appliances and non-airtight solid-fueled fireplace stoves." The old stove was a non-airtight wood circulator, so I guess that explains why it was installed.. ironically, my Avalon until recently was also technically not air-tight (bought it used, had to replace gaskets & handle to get good door seal)