Block Off Plate Made (Pics & Questions)

[Stax]

After getting home with the above sheet metal (it says welded steel in pic), I also failed to realize that it isn't galvanized. I was too busy looking at the size and gauge. Should I make another one from galvanized?

Also, the top of the firebox beneath the damper (lintel) is all metal or steel. How would you reccommend fastening the sheet metal block off plate to the metal or steel lintel (last pic)?

 

[jimbom]

I don't have enough experience to comment on how to install this plate, but with regard to the sheet metal go ahead prime and paint. Millions of tons of steel are in service that have never been galvanized. Do a first class job on the prime and paint coats and it should serve well for a long time.

 

[My Oslo heats my home]

Not sure how you would secure that. Most likely you would have drill some holes into the lentel or bring in the welder from the garage. My chimney company uses the heavy duty balloons in the old flues.

 

[bpm44]

Prime it and paint it - that's the same stuff I used and it's holding up fine. Some self tapping screws would hold that in place. If the lintel or other surrounding areas are 1/8" or thicker pre-drilling the holes for the self tappers will greatly ease the process. Nice fab work so far!

 

[Stax]

What kind of primer and paint should I use?

 

[begreen]

I would secure it with 1/2", #8 or #10 self tapping sheet metal screws. Drill clearance holes in the damper seal and hold it up in place. Take a Sharpie marking pen and mark the hole locations on the metal firebox. Then remove the damper seal and pre-drill tap holes in the metal. Put a bead of silicone on the flange of the block-off plate and mount in place with the screws.

 

[Stax]

BG, thanks so much. Being brand new at this, what do you mean by drilling clearance holes in the damper seal?

 

[Defiant]

BeGreen x 2, I believe he suggest a pilot hole to perfect the installation and make it easier to secure.

 

[begreen]

The holes along the flange of the damper seal need to clear the screw threads so that the screw doesn't try to tap into the block-off plate. They are clearance holes and should be slightly larger than the thread of the self-tapping screw. I would put about 3 on the short sides and 4 on the long sides. The tap screw hole (pilot holes) in the metal firebox need to be slightly smaller than the screw thread so that the screw bites into the metal and holds. If you hold the screw up and place the drill bit behind the screw you want to size it so that the drill is just a little bigger than the shank of the screw and smaller then the outer threads. Self-tapping screws have coarse threads, so this is easier than it sounds. Try it at the hardware store and get help if unsure.

 

[michaelreinard]

My chimney liner comes down through the damper at one angle NS and another angle EW, with not too much clearance above the stove so I don't have much room to wiggle it. I knew there was no chance I was gong to be able to cut the hole (oval) correctly the first, 2nd, or even 3rd time if I installed the block-off plate ahead of time. For that reason, I installed the stove and liner first, and built a 2-piece block-plate as on the attached picture. The rock-wool sheets are stuffed tight into the chimney throat, around the liner, and the sheet metal is basically there to keep anything from falling out and reflect heat.

Cardboard cut outs were key to getting it right the first time.

 

[bpm44]

As far as paint goes I used satin black high heat barbecue paint. It was the Ace hardware brand. Be sure to wipe down the the metal first to remove any oils. I used some brake cleaner for this since I had some in the garage.

 

[Stax]

Mike, thanks for sharing how yours was done. I will cut my hole once I get the liner. I think I will install the block-off plate ahead of time as I only have 3" of clearance between top of insert and bottom of fireplace opening. I've got a 3/4" board of Kaowool (18"x36") that I will probably double up on top of the block-off plate. I also used cardboard templates for measuring and cutting.