Makeshift blockoff plate

[stejus]

Thanks to the great number of posts that discuss a block off plate, I thought I'd ask about my approach now that I want to do this. I recently had an HI300 installed with a 6" flex pipe sealed at the top of the chimney. My installer said the clay liner was too tight to have a wrapped insulated liner so he will pour in some dry mix and add water to form an insulated liner. This can not be done until spring though.

So at this point, my damper is wide open. I thought if I could cut two pieces of sheet metal (28 gauge) and somehow lie on each side of the stove pipe it would help stop some of the heat from going up my chimney.

Will this help some even though it's not a tight seal or am I wasting my time?

 

[BrotherBart]

When you do it why not cut half circles in the pieces to fit around the liner?

 

[bsruther]

I had to cut my block off plate to fit when I got it. If I had known that it was just made of sheet metal, I'd have made it myself. It would be nice if you could find a template for the hole part.

 

[stejus]

I guess my only concern is this sheet metal resting up there and not screwed or bolted on. I'm thinking it may float/rattle seeing there's a lot of heat coming off the top of the stove.

 

[bsruther]

Here are instructions for making one.
https://www.hearth.com/econtent/index.php/articles/making_a_block_off_plate/

 

[stejus]

Thanks to the great number of posts that discuss a block off plate, I thought I'd ask about my approach now that I want to do this. I recently had an HI300 installed with a 6" flex pipe sealed at the top of the chimney. My installer said the clay liner was too tight to have a wrapped insulated liner so he will pour in some dry mix and add water to form an insulated liner. This can not be done until spring though.

So at this point, my damper is wide open. I thought if I could cut two pieces of sheet metal (28 gauge) and somehow lie on each side of the stove pipe it would help stop some of the heat from going up my chimney.

Will this help some even though it's not a tight seal or am I wasting my time?

consider jamming tightly mineral wool & jamming neatly an underlayer of al foil to minimize air infiltration

I know i can get al-foil readily. Is my only option for mineral wool through the web or can this be found at the retail level?

 

[drdoct]

I couldn't find any except off ebay. Mine was in Tennessee. Blockoff plates are really easy to make and you just drill a few holes in the easy to get to part of the flange part sticking down and put some tapcon cement screws into the brick. My template was from the link above. I'm not sure if I used the right insulation though. mine was ceramic 1" thick insulation that is used to line muffle furnaces. It was heavy and I'm happy with how much heat it reflects. I bought 2 feet and it was barely enough. Then I went around where the metal contacts the bricks with some of that fireplace sealant that's in a caulk tube. I'm going to have to redo with hitemp silicone soon because that other stuff sucks. It doesn't get very hot at all though. Much cooler than I thought.

 

[stejus]

I couldn't find any except off ebay. Mine was in Tennessee. Blockoff plates are really easy to make and you just drill a few holes in the easy to get to part of the flange part sticking down and put some tapcon cement screws into the brick. My template was from the link above. I'm not sure if I used the right insulation though. mine was ceramic 1" thick insulation that is used to line muffle furnaces. It was heavy and I'm happy with how much heat it reflects. I bought 2 feet and it was barely enough. Then I went around where the metal contacts the bricks with some of that fireplace sealant that's in a caulk tube. I'm going to have to redo with hitemp silicone soon because that other stuff sucks. It doesn't get very hot at all though. Much cooler than I thought.

if it dont get that hot, fiberglass might do the trick...fglass wont burn but melts to glass & stinks when it does.

Not looking to mount anything perminantly because the sweep is going to install a blockoff above the smokeshelf in the spring. He needs to do this so the insulation (poured in from the top) doesn't fall through. Anything I do now will be removed once he comes back in the spring.

So, if I stuff fiberglass insulation in the gap and then put some foil up there to hold it back, that may do the trick?

Does anyone know how hot a stove pipe gets at full throttle (first 15 minutes after reloading stove)? I don't want this to melt and stink.

 

[Defiant]

Go with the fiberglass insulation and use wire cloth to keep it there, its an easy and temp fix until the permanent install is done.

 

[karl]

Why add water to a dry mix. If that stuff sets up you'll never get it out if you need to.

Why not just put a block off plate in and then fill it with expaned vermiculite. It will insulate and if you ever need to get in there you can remove the block off plate and sweep it up and reuse it.

 

[stejus]

Why add water to a dry mix. If that stuff sets up you'll never get it out if you need to.

Why not just put a block off plate in and then fill it with expaned vermiculite. It will insulate and if you ever need to get in there you can remove the block off plate and sweep it up and reuse it.

Thanks, good point. My sweep is the one that is doing it. I mention this and see how he reacts. Your right in your comment. If i every need to replace the stove pipe or what ever else in the clay liner, the dry mix will be a lot easier to remove than a harded mix.

 

[drdoct]

Have you already paid for the pouring and blockoff part? I would think that would be double or triple the price of a regular install. Sure it would be perfect, but what if you want to get it out one day? If you've already paid for it then go for it, but if he's going to hit you with a $2000 bill after filling it, then I would just suggest doing a blockoff plate. Something else you could do is have him come and put in the block off plate that he's going to use. I would think it would have to be a lot heavier weight than I used though.

 

[stejus]

Go with the fiberglass insulation and use wire cloth to keep it there, its an easy and temp fix until the permanent install is done.

I think i understand what your saying. Lay fiberglass batting in the void (actually in the smoke shelf). Take a peice of wire mesh and get it to stay and this will hold back the fiberglass from falling. I think I may even line the wire mesh with aluminum foil to limit the air infultration back into the firebox.

Thanks for the quick fix. I hope to do this soon. I'll measure the before and after to see if it really helped!