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  #41  
Old 02-03-2013, 01:25 PM
Master Builder
 
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Default Re: Alternative Insulation

Thank you for pointing me in the right direction.
It gives a basis to understand how values relate to one another!
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  #42  
Old 02-03-2013, 04:38 PM
Master Builder
 
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Location: Tochigi Prefecture, Japan
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Default Re: Alternative Insulation


Now more confused than ever!
found a reference document: SCHUNDLER COMPANY--Perlite Insulating Concrete--Application and Design Information for Contractors

This lists properties of vermiculite concrete, 1:4 ratio to 1:8 ratio in both Imperial and Metric units.

there is a "K" value in imperial as .83, making the R value for 1:4 (1"thick) being R 1.29 (crazy small)

In metric units:
there is a "k" value same ratio in w/m k as .12, making R value 8.33
(pretty good).

The "R's" in my mind to not coincide with the "R's" for metric, even though I understand metric lengths and weights--

In Australia, what is a good R value for insulation?
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  #43  
Old 02-04-2013, 02:27 PM
Master Builder
 
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Location: Tochigi Prefecture, Japan
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Default Re: Alternative Insulation

Gave up!
The deeper I dig, the more decimal points and "letters" pop up!
Guess just knowing the relationship in principal is enough.
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  #44  
Old 02-05-2013, 02:38 AM
david s's Avatar
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Default Re: Alternative Insulation

Quote:
Originally Posted by mikku View Post

Now more confused than ever!
found a reference document: SCHUNDLER COMPANY--Perlite Insulating Concrete--Application and Design Information for Contractors

This lists properties of vermiculite concrete, 1:4 ratio to 1:8 ratio in both Imperial and Metric units.

there is a "K" value in imperial as .83, making the R value for 1:4 (1"thick) being R 1.29 (crazy small)

In metric units:
there is a "k" value same ratio in w/m k as .12, making R value 8.33
(pretty good).

The "R's" in my mind to not coincide with the "R's" for metric, even though I understand metric lengths and weights--

In Australia, what is a good R value for insulation?
Yes it seems that you are right. There are two different numbers depending whether you are using imperial or metric measures.
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  #45  
Old 02-05-2013, 07:48 PM
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Location: Detroit
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Default Re: Alternative Insulation

R Value is the inverse of K Value with K value being thermal conductivity. Thermal Conductivity in metric is measured in Wm−1K−1. Thermal conductivity in Imperial is BTU/(hrft⋅F). So yes, the R value would be different.
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  #46  
Old 02-06-2013, 06:05 PM
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Location: Tochigi Prefecture, Japan
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Default Re: Alternative Insulation

Thank you all for helping me to understand K,R,W,U and their metric counterparts. Far from understanding fully but at least aware of their relationships.

Back to "alternative insulation", I still believe that sand can be used as an insulator effectively. It is used as a medium in the castings of aluminum --it conducts heat away from the molten metal but the outside of the mold can be nowhere near the temperature of the metal--so it is an insulator as well.

How about this scenerio:
Any kind of an enclosure can be made from native materials, wood, scrap metal, stone-- (virtually anything easily available). Make this enclosure or base large enough and strong enough to contain a large quantity of sand.

The site should be high enough so that water does not flow under the enclosure and the bottom of the sand layer should be protected from water to prevent wicking.

Now if you built your WFO on top of this, with a layer of anything that would distribute the combined weights of the hearth floor and the oven dome. The sand would act as an insulating medium.

All the points mentioned before come into effect.
-using the sand to create air spaces.
-making the air spaces captive
-prevent heat loss by conduction (small particle to particle contact), conduction decreases with depth of sand base.
-utilize the sands -"real nature" as a heat sink.
-keep water away to prevent cooling via evaporation.
-a cheap, almost universally available material.

The longevity design success would depend the materials used to contain the sand. Wood & Sticks, vs Cob & Reed, vs Stone & Mortar. And the sub-base which the whole thing is built on.

Is that a "Three Little Pigs" story?

IMHO, water is the culprit in all builds. Because of its "possibly best - fluid conductor of heat", and problems associated with relatively low phase temperature change.
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  #47  
Old 02-06-2013, 09:35 PM
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Default Re: Alternative Insulation

Quote:
Originally Posted by mikku View Post
I still believe that sand can be used as an insulator effectively.

Use sand in your build as insulation, then report back and prove the world wrong.
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  #48  
Old 02-06-2013, 10:01 PM
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Default Re: Alternative Insulation

...unless he has a commercial bread/pizza oven and wants lots of thermal mass to maintain heat over years and decades (ie. never letting it cool down)
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  #49  
Old 02-06-2013, 10:38 PM
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Default Re: Alternative Insulation

Hello again-"The three little pigs guy!"

I am not trying to prove anyone in the world wrong, or attempting to use it in my build. I can get insulative materials where I am and choose by my budget which to use.

The author of this thread is in Kampala, Uganda and asked about "alternative insulations" and I am trying to rationalize alternatives.

Designs have morphed since the beginning of this forum. Early designs showed pericrete "below" a concrete slab, then a firebrick hearth. Is it that wacky to consider sand a better insulator than reinforced concrete? From what is listed, pericrete isn't that "red hot of an insulator either!" but it works!

I guess the question gets tossed back to NeilB-- "What do you have to work with in Uganda that is plentiful, cheap, has at some insulative values, doesn't melt at oven temperatures, doesn't off-gas hazardous chemicals? From where I am typing, I cannot see Uganda or even guess what the conditions might be.

NeilB--some feedback from you is necessary!
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  #50  
Old 02-06-2013, 10:54 PM
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Default Re: Alternative Insulation

Quote:
Originally Posted by mikku View Post
I can get insulative materials where I am and choose by my budget which to use.
Use goose feathers, as this is obviously a wild goose chase.
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