Newbie with Fisher insert

JBad

New Member
Aug 4, 2020
2
Central NY
Hi all, i've recently acquired a full size Fisher insert, i'm curious as to what size liner to install. I've read that an 8" is what is recommended but 6" will work as well and is less costly! My biggest concern is that the chimney is only about 13' from hearth to top of chimney and wonder about it drafting properly. Any help is greatly appreciated!
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
21,908
central pa
I find 7" actually works best
 

coaly

Fisher Moderator
Staff member
Dec 22, 2007
3,895
NE PA
What is the square footage of heated space you're heating with the Insert? Is there a blower on it?

Is the 13 feet from hearth floor to chimney top, or stove top to chimney top?

One good thing about Inserts is no elbows, tees or connector pipe to reduce draft. Insulate liner right down to the outlet.

There are things you can do such as starting with screen in place to reduce resistance of flow when starting, no spark screen at top, less flue damper use, and of course insulate liner all the way to increase draft for the shorter chimney. Other factors such as trees, hills, lakes, or other obstructions can cause downdrafts and drafting issues, so it's difficult to tell you exactly how it's going to work. Just having a loft or second story that heat rises into quickly can be a reason for a higher chimney needed.
 

JBad

New Member
Aug 4, 2020
2
Central NY
Thanks holler, i was looking into 7" liner, i've read that you suggest using an app. adapter from stove to liner, 8" crimped down or just a 7"?Coaly, yes there is a blower on it, i mis wrote, 13' is from flue opening to top of clay tile. The insert is probably overkill for my 660sq.ft. cottage but it gets pretty damn cold in the Adirondacks during winter! I also have the original screen for it as well, the cottage is up on a 30' bank at the eastern end of a lake so usually a good breeze blowing down the lake! There is also a 16"dia. maple about 10' from the northern side of the chimney that will be coming down in the near future! Thanks again to both of you for your input.
 

coaly

Fisher Moderator
Staff member
Dec 22, 2007
3,895
NE PA
You will be OK with that chimney height with enough differential temperature between inside and outside of chimney. As an example, using chimney height table with temp difference; .04 (inches of water static draft) requires about 140* temp difference at 13 feet. A 20 foot chimney gives you .04 at only 80* difference. I'll try a pic of a table so you can see what to expect. You can see how it would be an issue if you were farther south without cold enough temps.

Heating half the square footage it is capable of, I'd chance an insulated 6 inch. The larger the diameter, the more capacity. And you won't need that kind of full BTU output. The larger diameter is less resistance, so it also helps with smoke roll in issues, but if you crack the door and let it preheat before opening fully you should be able to get away with it.

I would go 6 in case this drives you out, you're ready for something smaller and newer.

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