Block off plate - opinions please

Ctwoodtick

Minister of Fire
Jun 5, 2015
1,127
Southeast CT
If I’m not mistaken, stove gasket material can be used around the liner. That should hold up to the heat. I can’t imagine silicone will.
I’m hoping your setup gets the seal of approval from the pros here, bc I like the looks of this material better than trying to contort sheet metal to my very uneven fireplace/ damper area ( installer removed some of the back firebricks to make insert fit ). I’ll wait to see.
 
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therealdbeau

Member
Oct 16, 2018
146
VA
trying to contort sheet metal to my very uneven fireplace/ damper area ( installer removed some of the back firebricks to make insert fit ). I’ll wait to see.
\

Thanks for chiming in. I too was left, by installer, was left with a choppy damper area so this was my best idea. I hope it works out.
 

tadmaz

Feeling the Heat
Dec 21, 2017
314
Erin, WI
Is there any sheet metal involved? Most say that the blockoff plate is to literally stop airflow up, not just slow the airflow. Not sure if the foil backing will stop airflow.
 

begreen

Mooderator
Staff member
Nov 18, 2005
79,791
South Puget Sound, WA
The foil should effectively block airflow. Is the product Roxul Curtainrock?
 

therealdbeau

Member
Oct 16, 2018
146
VA
The foil should effectively block airflow. Is the product Roxul Curtainrock?
Yes, Curtainrock 40.

Any ideas on the to seal around the liner? It's a really tight fit but I figured I put a bead of silicon around it but it probably gets too hot for the RTV. Furnace cement? for cram gasket material in there or just leave it be?
 

begreen

Mooderator
Staff member
Nov 18, 2005
79,791
South Puget Sound, WA
It looks pretty snug. I would probably not bother, but you could stuff in some thin stove door gasket material around the pipe there.
 

BlackBetty06

New Member
Jan 27, 2018
35
SE PA
If you get high temperature silicon (the red stuff) it will hold up also. We use it on 10-12” boiler exhausts that regularly see high temperatures without problems. Of course if you forget to close the air intake you would likely see temps above what an oil fired steam boiler generates so your mileage may vary
 

begreen

Mooderator
Staff member
Nov 18, 2005
79,791
South Puget Sound, WA
Of course if you forget to close the air intake you would likely see temps above what an oil fired steam boiler generates so your mileage may vary
A wood stove flue can get over 1200º if the air is not closed down soon enough. Red RTV is only rated to about 600º. It gets pretty stinky when over baked at high temp.
 

Easy Livin’ 3000

Minister of Fire
Dec 23, 2015
2,514
SEPA
Hi all - just finished fitting my block off plate. Anything I should consider before caulking this thing in place? Also, is the high temp silicon going to hold up on the liner there? Not sure how hot that metal gets.

Thanks

Product used: https://www.grainger.com/product/ROXUL-2-x-48-x-24-Mineral-Wool-Foil-19NE83

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Oh yeah, that's a great idea. I would totally steal your great idea, but my plate is going to be visible. Still might, just would need to hit the foil with some grill paint. Is the rock wool ridged or floppy?

I've made two failed attempts with sheet metal. It's really hard!
 

Dmitry

Minister of Fire
Oct 4, 2014
794
CT
Cool idea, how did you make it stay in place?
 

HomeinPA

Minister of Fire
Jan 4, 2018
510
Central PA
I like it but like Dmitry asks...what's holding it in place? Pretty much looks like you made it slightly oversize and wedged it in there which likely would work but it theoretically could slide down when someone runs a brush up and down the liner. I'd not worry about the seal around the liner as much as making sure it can't drop down on top of the stove.
 

therealdbeau

Member
Oct 16, 2018
146
VA
Is the rock wool ridged or floppy?
It is pretty rigid, I'm struggling to think of something to equate it too. Maybe like styrofoam - if you want you could break it in half but otherwise it is solid. Not sure if that makes sense.

Cool idea, how did you make it stay in place?
It is very much wedged in there. Also there is a small shelf in the back of the firebox from where bricks were removed that it sits on top. Combined with a slight forward slope to the flex liner it is stuck up there pretty goods. I figured I'd run a generous bead of silicon around the perimeter which I think will help further to keep it in place.
 
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begreen

Mooderator
Staff member
Nov 18, 2005
79,791
South Puget Sound, WA
You could attach some 1" angle iron to hold it in place if uncertain.