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  #21  
Old 08-17-2009, 09:22 PM
Apprentice
 
Join Date: Jun 2009
Location: kansas
Posts: 134
Default Re: Insulation Efficiency

Are you talking about the insulation over the dome?

Could you use the blanket as part of the insulated hearth?

So are you saying that the insulfrax blanket is more efficient than the vermiculite?

We poured the insulated hearth this evening - I used 3.5 huge bags of vermiculite and almost 2 bags of portland cement. It wasn't enough to fill the form, so I made angles at each corner, just using bricks (regular bricks), to take up space. I wanted about 5.5 - 6 inches of depth, but I think I got about 4.5 -5 inches of depth. I would have made more, but I ran out of vermiculite and the store was closed. But if I were to get some more tomorrow, could I pour on top of what is already laid?

As far as extra thermal mass - we decided just to add more fire if need be....is that ok?

Cecelia
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  #22  
Old 08-17-2009, 09:45 PM
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Join Date: Jul 2009
Location: Cochrane, Alberta
Posts: 104
Default Re: Insulation Efficiency

yes, I was talking about the dome, not the insulated hearth. Can we just pour vermiculite over the dome without the blanket or do we still lose too much heat?

As far as adding more vermiculite tomorrow, that should not be a problem if you are just pouring more over the dome....
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  #23  
Old 08-18-2009, 06:32 AM
Apprentice
 
Join Date: Jun 2009
Location: kansas
Posts: 134
Default Re: Insulation Efficiency

I was actually talking about the insulated hearth - Can I add to it even a day (or more?) after it's poured?
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  #24  
Old 08-18-2009, 07:07 AM
Il Pizzaiolo
 
Join Date: Jan 2007
Location: Tampa, FL
Posts: 1,446
Default Re: Insulation Efficiency

There should not be any problems adding more vermicrete to the insulating slab. Adhesion should not be a problem - the stuff is pretty rough and porous, so it will bond just fine with the previous layer. It is also under compression when completed, so nothing will be moving around.

RT
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  #25  
Old 08-18-2009, 12:55 PM
papavino's Avatar
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Join Date: May 2009
Location: Seattle, WA
Posts: 220
Default Re: Insulation Efficiency

I want to go back to Cecelia's question about whether you can use the Insulfrax blanket in the hearth. I would say no. You want something that will be structural like FB Board or vermicrete. The blanket has no compressive strength.
And to answer the question about efficiency, the blanket is more efficient than vermiculite. If you were to cover your dome in vermiculite, you'd need 5 inches compared to 3 inches of blanket to get roughly the same performance. I believe that's the consensus here. There's nothing wrong with using vermiculite to insulate the dome. You just need a thicker layer.
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  #26  
Old 08-25-2009, 09:17 PM
Serf
 
Join Date: Aug 2009
Location: Bay Area CA.
Posts: 13
Default Re: Insulation Efficiency

just thought I would add my 2 cents. My dome is Alfa Caminetti which is a lightweight refrax material construction. I set the hearth on two courses of firebrick with refractory cement then covered the dome with 2" of refrax and vermiculite blend.(looked like a huge oatmeal ball.) Then the entire dome was covered with loosely packed 20 cu. ft of vermiculite between the brick enclosure. The efficiency is incredible. I have had 1000 plus temps that 24 hours later are still sustaining temps of 2-250 degrees. I have been burning seasoned almond which is a nice hot wood and good coals.
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  #27  
Old 09-26-2009, 11:50 AM
philiph4@ameritech.net's Avatar
Peasant
 
Join Date: Aug 2009
Location: Farmington Hills, MI
Posts: 26
Default Re: Insulation Efficiency

The e-book says 2-3 inches of Insulfrax Blnket is enough insulation. I have enough 8#, 1" Kaowool to cover my oven with 2 inches. Is this enough or should I buy another roll? I am planning an igloo design and want to stucco right over the Kaowool.
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  #28  
Old 09-27-2009, 09:28 AM
Il Pizzaiolo
 
Join Date: Mar 2009
Location: USA
Posts: 1,436
Default Re: Insulation Efficiency

Quote:
I am planning an igloo design and want to stucco right over the Kaowool.
The question of is it enough is just a matter of how much heat you want your oven to retain.. I used the 8# kaowool too 2-3 inches, then about 4-5 inches vermicrete, then stucco..

I can cook all night and still have 400-500 degrees in the morning if i leave the door on,,
Im sure you would be fine with that plan for pizza's but baking may be a problem..

Just my opinion,, Mark (not an expert)
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  #29  
Old 09-29-2009, 05:50 PM
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Join Date: Feb 2006
Location: Eastern NC
Posts: 910
Default Re: Insulation Efficiency

That's about what I get, too.

2 to 4 inches of ceramic insulation with 4 to more inches of loose vermiculite and 2 inches of FB board underneath.

Christo
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  #30  
Old 09-30-2009, 06:38 AM
philiph4@ameritech.net's Avatar
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Join Date: Aug 2009
Location: Farmington Hills, MI
Posts: 26
Default Re: Insulation Efficiency

I thought that I read FB is now recomending Ceramic blanket only insulation. Has anyone else read this? If so, how much is required. The Ebook says 2 to 3 inches is enough.

Phil
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