Is it possible to close one side of two-sided fireplace with airtight seal?

[Margie]

Hello! I've been doing extensive research trying to find a way to solve the smoking issues in our see through masonry wood burning fireplace. Here are the details, thus far:
- The fireplace sits between a very large kitchen and a much smaller den.
- We know the flue is too small (13" square for two openings each apx 34"x30").
- The damper is 7" wide x 30" long and functions properly, although it is offset much closer to the kitchen side of the fireplace, creating a 'shelf' on the den side (the side that smokes).
- We added an Enervex fan which has helped a lot with the draw issue, but has not completely prevented the smoke from spilling into the den.
- We then tried raising the grate, which in conjunction with the fan, helped, but still didn't completely solve the problem.
- We then roughed in a piece of plywood to cover the den side (simulating doors) but a little smoke still seeped out (even with the raised grate and fan running). This got MUCH better when we duct taped the gaps between the plywood and stone, and we had no spillage at all when we burned a fire for several hours.

Based on our experiments above, it seems that our problem could be solved with installation of a fixed Neoceram or Pyroceram panel with fireproof sealant on the den side ((to create an airtight seal, tighter than what could be achieved with doors), and a simple screen on the kitchen side. I understand that these ceramic 'glass' materials are extremely heat resistant, so there shouldn't be an issue with them breaking, particularly since the fire would be several inches away from the surface (32" deep firebox, and we're keeping the grate closer to the kitchen opening. This would allow us the functionality of a trouble free single sided wood burning fireplace, with the look of a see through fireplace. However, despite multiple Google searches and contacts with industry experts, I have yet to find anyone who has done this, and even more importantly, anyone who has done this successfully. Does anyone have any experience with this? If this is a feasible solution, I'd like to know the best way to proceed and find a local resource that could assist with measuring and installation.

 

[jatoxico]

I dont see anything wrong with your idea but it would be a fully custom job. If you tested the setup and are satisfied with the result then the ceramic glass should work just fine. Sounds like it will be pricey and being such a unique application it will be hit and miss if you can find someone in your area with the skills to pull it together. Maybe someone skilled in working with stained glass.

 

[Hogwildz]

Close one side off, and put an insert in there.

 

[begreen]

Seems doable. One solution would be to bolt a 1" angle iron frame in the fireplace opening that is bedded in silicone. Then drill out a thinner piece of 1/2" flat stock every say 6". This is to hold the glass captive. Cut the flat stock to match the angle iron faces, mark the holes from the flat stock onto the top edge (closest to the brick) of the angle iron. Drill out the angle iron holes. Measure for the glass to just inside of the freshly drilled holes on the angle iron and get it cut. Put a thin bead of silicone on the outer edge of the angle iron and set the glass. Gently secure the flat stock in place to hold the glass in place but be careful to not take the bolts much more than hand tight. You should not need more than to just start flattening the silicone bead. Let set up for 24 hrs.You could also use adhesive backed, stove glass gasket tape on the edge of the glass.(broken link removed to http://woodheatstoves.com/breckwell-pellet-stove-glass-gasket-34-inch-x-18-inch-x-10-ft-p-9703.html?cPath=292_90_114)

Or just buy a set of these:
http://www.fireplacedoorsonline.com/acatalog/Air_Tight_Doors.html.

 

[weatherguy]

I have a two sided fireplace too but never use it, if I was to use it I would close off one side and put an insert in, still haggling with the wife over that one. If you want to use the FP I think the easiest solution is Begreens link to the airtight doors. Ive thought of buying a couple of those doors and having occasional fires but it would run about $3,000. Could get an insert and install it for that and get more heat.

 

[Margie]

Thank you all for the feedback.

begreen, do you know if those doors are truly airtight? Based on our experiments, we were only able to completely avoid smoke by duct taping every little gap on the sealed side, so I think we would need an airtight solution to completely avoid smoke. There were doors on the fireplace previously, but smoke would still spill out (although, the doors were quite old, so maybe didn't function as well as a new pair would?). It seems like the fixed panel would be the best solution, and would be less expensive than doors, but a little daunting considering I have yet to find anyone who has actually done it.

Hogwildz and weatherguy, I'd like to exhaust the above possibility before considering an insert, as we like the aesthetic of the two sided fireplace. However, may pursue the insert route depending on what we find.

 

[mcollect]

Four years ago we were in your situation. My wife loves fires so we had the architects design a two sided fireplace between the living room and the dining room. Well it never worked well and the glass on the dining room side kept exploding. We had a blacksmith build a metal and glass shield for the dining room, it was a perfect fit but it still smoked and made the house cold when use. She wanted a stove but when I took her to see them she fell in love with a Jotul 550. We had it installed in the living room side and left the fancy shield in the dining room. This has been the best thing that we did to our house! The insert keeps the house warm and no furnace to eat up money.

 

[Margie]

Thanks, mcollect. Did you experiment prior to installing the shield to ensure putting it in on the DR side would solve the problem? And, does the shield make an airtight seal? I ask because we've done multiple tests, and the kitchen side of our fireplace functions perfectly when the den side is sealed off.

I've seen other posts referencing the Jotul 550, so I'll look into that.

 

[begreen]

The doors are "supposed" to be airtight. Call the mfg. to confirm. FWIW, I would imagine, with some silicone, that most fp doors could be made fairly airtight.

http://www.lowes.com/Heating-Cooling/Fireplaces-Stoves/Fireplace-Doors/_/N-1z0zq3h/pl

 

[Margie]

Thanks, begreen. The link you sent shows all tempered glass doors, but I'm inclined to go with a ceramic material (like Neoceram or Pyroceram) to avoid shattering like mcollect experiences. Thoughts??

 

[begreen]

Could have been a flaw in mcollect's architect's design, especially if he was trying to totally enclose the fp in glass. I would think that If the other side is always open, then it should be ok with tempered glass. You were test burning with plywood there right?

 

[mcollect]

The trouble with tempered glass is the sides. Any pressure on them and the glass is shattered. So the seal has to be on the front and back of the install. Ours was encased in silicone but the expansion of the glass put pressure on the sides and BANG.

 

[Margie]

I'm looking at ceramic, not glass - http://www.fireglass.com/glass/neoceram/#Features - much more heat resistant, so (fingers crossed), won't have any issues with breakage. mcollect, this is a bit of a reach, but I'm in B'more, and if your blacksmith guys isn't too far, and if you'd recommend him, I'd like to contact him to see if he's interested in my project. Can you send me his info? I have a local glass guy and a local metal guy I know that I'm going to reach out to, also.

 

[begreen]

It doesn't sound like high heat shattered mellow's glass. The way he described the problem it sounds more like thermal expansion was the issue. Ceramic glass will also need expansion room. Be sure your installation accommodates for this.

 

[jatoxico]

It doesn't sound like high heat shattered mellow's glass. The way he described the problem it sounds more like thermal expansion was the issue. Ceramic glass will also need expansion room. Be sure your installation accommodates for this.

No expert but I believe the ceramics have coefficient of expansion of nearly zero.

 

[begreen]

Good point ja. I definitely am not either so I have to defer to the mfg's specs on that. I looked up neoceram and this docs confirms your statement. Thanks.

http://www.midori-tech.com/Neoceram Catalogue.pdf

 

[Ashful]

I'm surprised that you find the one side has to be airtight, and as begreen already suggested, I'd be concerned with any solution that does not permit some movement between the ceramic glass panel and the surrounding masonry. All materials have some CTE, and despite ceramic glasses being very low, you need to account for shear size (multiply your ppm by the size of the panel), and the not so well-matched surrounding materials.

It appears you already understand the importance of opening size to flue cross section ratio. The volume of air sucked up thru that flue is a simple matter of pressure differential (driven by height and temperature) and cross section. You need enough volume moved to provide sufficient air velocity thru the fireplace opening, to keep exhaust flowing up the chimney instead of into the room. If you're closing off one side and still seeing smoke leak out the gaps around your panel, it's likely more an issue of directionality than anything else. Perhaps some interior baffling could get the low pressure where you need it / get the air currents in the right direction, so that the ceramic glass or doors need not be airtight.

Me? I'd be installing a free stander at a 45 degree angle, viewable from both rooms.