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jimkramer 08-15-2012 06:26 AM

vent made of insulating brick
 
I'm trying to minimize the amount of insulating board I'll use, because it's very expensive. (I'm not even sure yet if I will use board or vermicrete.) Can I make the vent arch and landing out of insulating fire brick? That way I wouldn't need board under it. Then I could probably get away with 18sq ft instead of 24. That would amount to one less FB board. Or, because other suppliers only sell by the box, that would mean one less box to buy and ship. Waddya think?

dottavio 08-15-2012 10:01 AM

Re: vent made of insulating brick
 
I think what you are trying to do is create the vent/chimney area in front of the dome from insulating brick. If I am correct there is another option that I am looking into now....

You can create a thermal break between the dome and the vent/chimney by leaving a gap between the two and adding a thermal break in the floor.


http://www.fornobravo.com/forum/f8/g...ome-18207.html


This way you can use regular fire brick for the vent/chimney area, which will be stronger than insulating brick, and insulate with insulating concrete under and over the vent if you choose

I opted to use a perlite/portland insulating concrete mixture. I felt it was stronger than the insulating board, and cheaper, to support the load of the oven. Although many have used FB board successfully. Just my preference.

Doug O

deejayoh 08-15-2012 10:32 AM

Re: vent made of insulating brick
 
I would say no for two reasons: 1) Insulating bricks are super spendy, not sure what savings you will have here and 2) they are super fragile and not at all suitable for use in the opening of your oven where you are going to have the most contact with peels, pans, and general hard knocks.

but.... for the arch and landing, I personally feel you can get away with far less insulation and probably even use normal brick for the build. The qualifier to this is that you would need to employ a heat break between you dome and entry in your build design. The landing is not a cooking surface, and it doesn't get that hot so you don't need it to retain heat and you shouldn't have spalling issues. And if it is separated from the dome by a heat break, it won't be sucking the heat out of your oven so you have less of an issue with insulation. The only place I might think about using firebrick is at the inside edge of your flue/top of your inner entry arch. That area is exposed to all the gasses coming out of the oven and can get up there in temperature.

jimkramer 08-15-2012 10:36 AM

Re: vent made of insulating brick
 
I guess that would work, too. I was thinking to make the vent/chimney area out of insulating brick so I wouldn't have to mess with perlite or vemiculite at all. I thought maybe if you use conducting firebrick (common red brick), you'll still need insulation under it, even with a thermal break, which won't stop all heat from the dome.

GianniFocaccia 08-15-2012 12:22 PM

Re: vent made of insulating brick
 
Sorry Jim,

I thought you were inquiring about insulating your vent area (entryway) with IFB. Many builders (including me) at one time have inquired about building parts of their entryway vault using IFB, which, as Dennis notes, is not suitable. I also believe IFB is not acceptable from a safety perspective. The stuff chips and abrades quite easily and could end up in your food.

Now, for insulation under your entryway, this would work, but again, IFB's are pricy. Maybe just go with vermicrete?
John

deejayoh 08-15-2012 01:04 PM

Re: vent made of insulating brick
 
Quote:

Originally Posted by jimkramer (Post 136741)
I guess that would work, too. I was thinking to make the vent/chimney area out of insulating brick so I wouldn't have to mess with perlite or vemiculite at all. I thought maybe if you use conducting firebrick (common red brick), you'll still need insulation under it, even with a thermal break, which won't stop all heat from the dome.

insulation under the arch won't really stop heat from leaving the dome either. It's an open area exposed to the air. The reality is that we all insulate under the vent, and then leave maybe 4 times the surface area of the floor directly exposed to air through the entryway. That surface is a giant heat sink pulling thermal energy out of the dome if there is no a heat break. That's why I say you could probably get away w/o insulating under, but with a heat break

But as John suggests, perl/vermicrete is a pretty cheap way to go if you want insurance. And it probably is easier to install the a uniform layer of insulation under both your dome and entry when you get started than it is to figure out what you are going to use to make the whole thing the same level with no insulation under part of it..

GianniFocaccia 08-15-2012 01:17 PM

Re: vent made of insulating brick
 
Quote:

insulation under the arch won't really stop heat from leaving the dome either. It's an open area exposed to the air. The reality is that we all insulate under the vent, and then leave maybe 4 times the surface area of the floor directly exposed to air through the entryway. That surface is a giant heat sink pulling thermal energy out of the dome if there is no a heat break
I can't attest to the effectiveness of a heatbreak, but since I plan on having my outer arch barely contact my oven's inner arch, I am planning on insulation under and around my entryway and flue as insurance. I agree, an exposed entryway (and open flue) will act as a giant heatwick (is that a word?). I think an inner and outer door is in order here, which makes the ability to utilize an enclosed entryway as a holding/warming area a practical idea.


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