sealing the chimney

My fireplace is open on the front and right side so my coal insert just sitting inside. The 6” flue liner goes up the masonry chimney and was insulated under the top plate when it was installed. This year I like to seal the chimney at or close to the damper since at some point the liner will fail and I don’t want a CO poisoning problem, plus to reduce heat loss.

I came across these instructions and it sound like it would work and isn’t too difficult. Since I never worked with metal sheets and don’t have the tools, I figured I ask for some advice if I am on the right track and any guidance you guys might be able to give me.

http://www.hearth.com/econtent/index.php/articles/making_a_block_off_plate/

I did something very similar to this setup, except I inserted my stove pipe into the inside of the liner as opposed to over the liner as the picture shows. Doesn't hurt to stuff some insulation in before sealing off the old damper too.

I'm actually going to be embarking on this task here; hopefully tonight I can get it started. Since I've got an older hand laid chimney and nothing was square the past few times I've attempted this have been less than satisfactory.

I'm going to attempt to make a template out of cardboard first, then I'm going to transfer it to tin, then if that works hopefully I can take it to the steel mill by my house and have them fabricate something a bit nicer.

I've tried using that how-to before, the problem I have is my chimney is stone, so it's really uneven. I think I'm going to print the thing out this time and have it with me for reference.

Reading the link you posted I'm assuming you'd take all your measurements at the floor? Would that even work?

I'm On Fire wrote:I've tried using that how-to before, the problem I have is my chimney is stone, so it's really uneven. I think I'm going to print the thing out this time and have it with me for reference.

How does the damper seal against uneven stone?

carlherrnstein wrote:

I'm On Fire wrote:I've tried using that how-to before, the problem I have is my chimney is stone, so it's really uneven. I think I'm going to print the thing out this time and have it with me for reference.

How does the damper seal against uneven stone?

Magic.

Seriously, there's brick inside the chimney but it too is not even..I need to seal the somehow.

I'm On Fire wrote:

carlherrnstein wrote:

I'm On Fire wrote:I've tried using that how-to before, the problem I have is my chimney is stone, so it's really uneven. I think I'm going to print the thing out this time and have it with me for reference.

How does the damper seal against uneven stone?

Magic.

Seriously, there's brick inside the chimney but it too is not even..I need to seal the somehow.

Make a cardboard template about 3/8 to 1/2" smaller to fit,then hammer drill 3/8" holes under the template and install bolts long enough to hold up the template. Make your metal damper from the template,when you install the metal damper you can use refactory cement or masonry cement to seal up the gaps at the stone/brick edges.On the metal damper weld a collar on the bottom of the plate the size of your stove pipe and screw the stove pipe to it. No stove pipe is needed above the damper.

Even 400-500*F RTV Silicone will work to seal the gap at the bricks...very little heat at that location.

Silicone will be a lot easier to apply in the overhead position also.

I started my template tonight. I loosely followed the link from the OP but since I've got stone once I got to the front I had to kind of wing it. The left side sticks out in the front about 1". But once the plate is done I'll trim it with a grinder. I have the hole for the stove pipe marked 3" off the back but I'm not sure if I should move it an 1" back. It just seems too far forward.

Once it's done I'm going to take it to RS Phillips Steel and have them fabricate a plate with a welded collar and mounting brackets on the sides and the back. I'll screw what I can then fill with high temp silicone.

I didn't want to start a new thread since this is a similar question. I will be running 6 inch round black stove pipe into a 7 1/4 square chimney flue tile at the base of my chimney where it enters my basement.. Since I remember from preschool, round pegs didn't fit well in the square holes so, what would be the most reliable way to seal it? stuff fiberglass insulation tightly around it? suggestions would be greatly appreciated

My buddy next door had a Lopi insert "professionally" installed and they packed the stove pipe with fiberglass at the stove pipe to rain shelf transistion.

I have been reading about fiberglass breaking down at "high" temps. Not sure what "high" is but mineral wool seems to be better to insulate. I haven't found any around at the stores but I did find a web site that ships it.
http://www.anvilfire.com/sales/pages/kaowool_index.htm

I just dropped my template off at the steel yard (RS Phillips Steel) to have it made. They said it'd be done in about two hours. I told them I'd pick it up next Saturday. Can't wait to see how they do with it.

Make a duplicate template, you will need it sooner or later

Whoops. Hopefully the don't butcher it. Or, I could just copy it from the one they make after I get it back.

I got my throat plate back from the steel yard this afternoon. Looks good and should work. There is,however one point of issue. The side brackets are 90° which they measured from the front. They were supposed to match the side angles. I did Tell them they had to be matched to the side angles so it could be bolted to my fireplace walls. I don't want to take it back to have it fixed because they'd likely charge me for it. As it stands I had failed to mention I needed several holes drilled in it along the front and the mounting brackets and when I did they put them in but I got charged more. My wife is a little annoyed because it cost more than originally quoted because of my failure to mention the additional holes.

What I'm thinking of doing is notching the bracket so it goes further and hope the one bolt into the fireplace wall will be enough to hold it up. Oh, the other issue is the angle for the back of the fireplace wall is wrong, I measured 60° and I think it's 45°. But considering the brackets are 1/8" steel I think I can force the angle when I bolt it in.

At any rate. I think it came out nice. I'll throw a coat of stove paint on the top and bottom get it bolted in place and then cement or silicone the gaps in the sides.

I did test fit it and I've got a little trimming to do on one side but it's not much.

Actually, looking at it again, I don't think I'll be able to use the other bracket at all it doesn't even have one edge that is flush with the edge of the plate. Unless I drill two new holes in the plate and add bolts from the top.

I'll figure something out.