Sealing off the smoke shelf: Fireplace insert

[Skier76]

I'm looking for the best way to seal off the smokeshelf/damper area of the fireplace. As you can see from the pic, it's pretty open. The installer said it would be "fine" that way. But that's too much cold air sitting in that column IMHO. I'm thinking of adding an OAK up the chimney, so that's a consideration.

What's everyone using? Block off plate? Rockwool? Both?

 

[digitys]

If that liner goes all the way up and is sealed at the top, do you need it?

 

[CleanFire]

We had a block-off plate fabricated at a local metal shop, you can use heavy paper or thin cardboard to mock up a template to match the flue opening / pellet pipe / holes needed to fasten,

the plate here is held on by metal 'clothes line' hooks which hook over / grab the top of the dampener, so it's easy to remove / re-install..

No gasket needed around the perimeter of the plate here, using stove gasket rope to seal around the pellet pipe & dampener hinge openings in the plate.

Metal is stainless steel, 1/8" thick, cost was about $75.00 IIRC - our plate was fabricated 10-12 years ago for the woodstove: I just adapted it for the pellet stove (pipe opening) this season.

 

[Bill L]

My installer packed it with insulation, heat resistant I presume. I took a picture last fall when I was trying to figure out how to instal an OAK, see attached

 

[CBL]

Pack the damper area around with rockwool, and make a tight fitting sheet metal block off plate for another layer of protection and sealing. Some folks use tack nails or silicone caulk to keep it in place, but can be a pain in the butt to remove if you ever need to take it off.

I'm not a fan of leaving insulation exposed. My concern is the distribution fan could knock any fibers off of the insulation and could blow back out into the room. Not terrific stuff to breath in.

 

[Skier76]

Great advice. Would some rock wool with some metal flashing work?

 

[Don2222]

The only insulation that is acceptable to use is 100% fire proof rock wool called Roxul

 

[CBL]

The only insulation that is acceptable to use is 100% fire proof rock wool called Roxul

I used roxul in my installation. But it doesnt have to be roxul branded mineral wool. I believe any mineral wool has similar fire resistant attributes to roxul.

A step above that is ceramic insulatation which is quite expensive. but the nice thing is it holds itself together much better than mineral wood does so its easier to install.

 

[Skier76]

Where's the best place to get insulation?

 

[CBL]

Lowes sells roxul. but the smallest quantity you can get of it is 15 batts. be prepared to have a lot of extra.

 

[Skier76]

Interesting! Looks like the Roxul doesn't have an R value. I assume this just blocks airflow?

 

[CBL]

Actually it does have an R value of 15 when applied into a 2x4 wall. I'm sure when its used in a wood insert application the R value is completely skewed. However you can rest assured that if you use enough of it to block the damper it'll be insulated.

 

[Skier76]

Thanks CBL. Seems like a worthwhile investment. It should stop the draft I'm sure that's happening behind the stove.