6" round into 8" square

Hello all. New to coal and about to install an older Grizzly Coal Cub with a 6" round vent I picked up a few years ago for cheap. Looks like it was seldom used if ever. I'll be installing it in my garage/shop. My house has a heavy gauge Heataltor fireplace with an excellent masonry chimney which I hope to put in a coal insert eventually. The back of the fireplace is exposed as a concrete block wall in the garage. Apparently, the previous home owner planned on a furnace of some type because the concrete block wall also has another chimney/flue that is accessible through an 8" round hole that feeds into a 8" square terracotta flue. After inspecting the flue it appears as though it has never been used. (the house has electric baseboard heat). My question to you all is can I run a 6" black stove pipe with a manual damper directly into an 8" adapter into the 8" terracotta flue without a liner or should I line the 8" with a 6" stainless steel liner? Also do I need a Tee section for a clean out and do I need a barometric damper? Thanks.

You don't need a liner if the clue is in good shape. Yes on black pipe.

Tee sections help. (Im assuming you mean where it leaves the stove in back) If you dont use one you have to keep and eye on the elbow as ash will accumulate. Its more work and messier without a tee is another way to say it. Im assuming you are using anthracite. If using bit then I'd go with a tee for sure.

The baro part is a matter of opinion. Your stove... Ive never seen or heard of this stove. If this uses a bimetalic air intake then a baro is less needed. I can see the large air spinner on each door.

I like the bear head! Is this a Fisher brand stove? I know they had a Coal Bear model.

woodshoe wrote: ↑

Thu. Nov. 10, 2022 10:34 pm

My question to you all is can I run a 6" black stove pipe with a manual damper directly into an 8" adapter into the 8" terracotta flue without a liner or should I line the 8" with a 6" stainless steel liner?

I would say no on the stainless steel liner. Instead of using an adapter, you can also just run the 6 inch stove pipe into the 8 inch terracotta then seal it by stuffing fiberglass insulation or rock wool around gaps. This is what I do since it seems I never had any luck finding a suitable adapter.

woodshoe wrote: ↑

Thu. Nov. 10, 2022 10:34 pm

Also do I need a Tee section for a clean out and do I need a barometric damper?

A Tee definitely makes it easier for cleaning and inspecting probable fly ash accumulation places. As far as a baro, I would say definitely yes on the the condition that your stove has no automatic way of controlling heat output. The baro limits the draft which in turn smooths out the curve for producing heat and makes the stove temp nice and steady. Otherwise the stove temp will oscillate with the draft pressure.

I used one of these to being 6” pipe into my 8” thimble, worked perfect.

https://www.northlineexpress.com/heatfab-8-male-t ... -5235.html

They also make a version with an 8” female in case you want a length of 8” pipe to slide in the thimble.

Holy moly. $57 for a reducer. Can't wait to replace my plpe next time.

Rob R. wrote: ↑

Fri. Nov. 11, 2022 10:27 am

I used one of these to being 6” pipe into my 8” thimble, worked perfect.

My terracotta liner is square with an outside dimension of 8 inches, I didn't see if the poster above was round or square.

accessible through an 8" round hole that feeds into a 8" square terracotta flue.

It sounds like a pretty typical setup. Should work well for a coal stove.

Thank you all. You folks are AWESOME! Very excited to set up this coal burner. "warminmn" this stove is not a Fisher. I think it's actually a Grizzly but not the same brand of Grizzly wood stoves I've seen advertised for tiny homes or boats. I once looked for the maker and I found a patent was applied for the design of the stove. I searched a found the guy that built them and he owned a steel fabrication shop that has since gone out of business. I think it was in Michigan or Indiana...not sure. Anyway, I searched for him and found he lived in Montana and now burns wood there because it's what's easily available. He knew the stove and also knew which employee welded it because on the bottom, underneath the welder etched his initials. He said it will put out a lot of heat burning anthracite. This conversation took place about 4 or 5 years ago. But, once again, thanks to all and I'm thankful for this forum.