Block-off Plate

[DenD]

I recently had an Osburn 1600 insert installed in an exterior chimney with a full SS liner. The manual doesn't call for the use of a block-off plate and when I asked the installer about putting one in, he said it wasn't needed and the stove may draft better without it. I have since read several posts on this forum about block-off plates and I was wondering if people think it would be a good idea to install one? And if the consensus is that I should put one in, are there any reccomendations on types/brands/stores? I would be looking to buy one as opposed to fabricating my own.
As always, thanks for all the great advice.

 

[webbie]

Draft better without it?

How?

It is generally more difficult to attempt to fit a pre-made plate - in other words, they should be fabricated on the job. The installer should have done it in my opinion. However, if your job is sealed well at the top and your panels seal very well at the front of the fireplace, then it may not be too bad as is.

 

[Mo Heat]

Draft better without it?

How?

I guess it's possible that all the heat coming off the insert/stove that goes up the chimney would tend to keep the liner a bit warmer, especially if it isn't insulated, but that's a lot of heat loss to the masonry for a likely smallish increase in draft.

My dealer and installer also told me I didn't need a block off plate and wouldn't install one for me. I think I'm losing a bunch of heat up my chimney area (around the liner) and so I'm planning on putting one in soon. I'll report back if soon ever gets here.

My main reason for a block off plate is to save some heat. I'm not too worried about decreasing my draft. I doubt that would happen. A block off plate should make a chimney fire (god forbid) a bit safer, too, I'd think.

 

[the_guad]

My installer doesn't do it as a standard, but I requested it and they did oblige after a few minutes. It's hard to get someone to do anything out of the ordinary but they were good about it in the end. Plus, they had the tools and the spare sheet metal already so they could fabricate it onsite.

 

[DenD]

Mo - That's pretty much how the installer explained it. The heat rising around the liner would keep it warmer and improve draft. To me it seemed like the heat loss would be fairly substanital, but being new to the wood-burning game I took the installer's advice and didn't push the issue. Please keep us posted if you retro fit a block off plate, I'd be interested to see how it works out for you.
As always thanks for the advice.

 

[JotulOslo]

When I installed my Jotul Oslo and stainless steel liner into my fireplace a few weeks ago I fabricated my own block off plate. I made a cardboard template to determine the shape I would have to cut out for the pipe. The template had two shiskebab skewers place 1/4" from the bottom that I used to make sure the template was alway in the same place as I went back and forth between cutting and scribing the outline of the pipe. Using two pieces of 8" X 18" steel plate I purchased from the local ACE hardware I traced the outline of the pipe on one end, drilled a series of holes with my drill press along the outline, and then used a hacksaw to cut out the material in between the holes I drilled. I then smoothed up the outline with my RYOBI oscillating sander table. I then cut the pieces to the appropriate length to fit my damper frame, with some overlap on the end for adjustment.

Along the bottom of the plates, at the same distance from the edge that I used the skewers on the template, I drilled and tapped two holes. These holes were used to attach to 3/8" EMT conduit clamps. I installed the two plates to make sure they fit, and then used a pencil to trace the outline of the rest of the damper plate. This allowd me to drill and tap two more holes on the top, again for screws and conduit clamps.

When everything had been test fit, I smeared a liberal bead of DAP High Heat fire resistant mortar outside the outline of the damper opening, installed the plate, and used the screws and conduit clamps to pull the plate tight to the damper frame. I also installed a bead of the DAP High Heat around the stainless steel flue.

It did take some time, but I got a result that I was confident in and knew was secure. Plus, I felt better about doing it myself. When I describe what I did to the shop I bought the stove from, they sounded pretty impressed.

Seems to work for me.

JotulOslo

 

[JotulOslo]

I know this is somewhat late, but I finally got around to taking a few pictures of my block off plate and thought some might be interested. The gap between the plate and SS liner will be stuffed with kaowool if the local refractory folks can get me some scraps. If not, I'll try to scrounge some somewhere.

JotulOslo

 

[elkimmeg]

What a bunch of BS the intrusion of room air is not going to heat up the liner. Snce when will 70 degrees heat a a flue liner already heater beyond 300 degrees?
The opposite is happening the room air is cooling down the liner therefore weakening the draft and leading to cresote build up.

Why did he not tell the truth? I'm to lazy to do it. At least he would be honest and not a bs artist