Sealing flex liner & block off plate

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esh21167

New Member
Hearth Supporter
Dec 27, 2007
48
Central PA
I'm in the middle of my fireplace insert install. The blockoff plate is in place with a 8" diameter hole. Sealed that to the brick with 600 degree silicone. I have a 10" square SS plate with a 6 3/8 hole to slip over the liner. Made it in two pieces for moving the liner around to determine proper location. I'm reading here that I should use stove cement or stove sealer (cement in caulk form) to seal the liner to the blockoff plate, the two pieces of my plate, and the flex to stove connector. I'm a little worried because the cement dries rock hard. During liner cleaning if any movement occures at the liner/plate area will that break the cement seal? A few have told me that the 600 degree silicone is good enough. I found this Rutland sealer that might be OK. It's good to 800 degrees. Any thoughts?

http://www.rutland.com/productinfo.php?product_id=29
 
Eric, you have a legitimate concern that the stove cement will crack when you are cleaning the liner.
Beleive it or not, I sealed my block off plate with regular silicone and after one season everything seems to be ok.
This year after cleaning the chimney I will reseal my block-off with hi-temp silicone.
 
since there are no large gaps hi temp silicone should even if the silicone seal broke or the cement cracked you are talking minor , minor air movement ...
so i would def use silicone around the liner and you could use cement around the outer blockoff plate.... but honestly either one is fine and like anything check it because it may wear over time
 
From the wisdom of Brotha Bart, use some rope gasket between the liner & block off plate and no need for the other. Will not crack either ;)
 
I do recall reading a post about the rope gasket, now that you mention it. I already have some 1" kaowool on top of the plate, but gaps because of the oversize hole. After securing the second plate to make the hole tighter to the liner could I pack some of that in the gap? Doesn't seem quite as durable as the rope gasket though.
 
Try it, you have nothing to lose.
 
Hi,
Just wondering where you folks find hi temp insulation... The home centers dont seem to carry it and the folks at the stove store I called were perplexed that I would not just use fiberglass insulation "Just peel the paper backing off of it..."

I would like to buy enough for the block off plate and the back of the fireplace befor eI put my insert in. Preferably I would like to find a local store because I plan to install this weekend. Thanks!
 
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