Heat loss thru insulation board

[dbhansen]

Does anyone have thoughts on how much heat loss is "acceptable" through the insulation board and into the hearth? I am considering a material that, according to the manufacturer's calculations, will reach about 206 degrees F on the side opposite an 1100 degree heat (assuming that heat is direct and constant). Does anyone know how FB Board compares to that? Is 1100 too high a number to use? I could have them recalculate it, but what's a realistic number (i.e., how hot does the base of the oven floor get)?

[CajunKnight]

What is the material? What kind of cost range are you talking about? Is it easily obtainable?

[asudavew]

I don't think your floor will hit that temp.

I could be wrong.

But the losses you are describing seem normal and acceptable to me.

[dbhansen]

The material is Insblok-19, which others here have used. The numbers I quoted were based on 2" panels. With 3", the outside will reach 171 degrees @ 1100 degrees inside.

[dbhansen]

Originally Posted by asudavew

I don't think your floor will hit that temp.

Reading other posts (which I should have done earlier ), it seems like 800 degrees may be more reasonable for the oven floor. At that temp, the manufacturer says the 2" board will reach 163 degrees on the outside (at 80 degrees ambient temp). That's more reasonable. Thanks for the input!

[RTflorida]

Maybe one of our thermocouple users can help in this.
In using my IR, the face temp of my hearth bricks goes off the scale (over 1050 degrees) directly under the fire, how much of that bleeds all the way through the bricks an into the insulation - I don't know. I used 4" of vermiculete as my insulation under the hearth. The highest temp I have seen through the insulation and through the support slab and 1/2" backerboard is around 125 degrees (after firing for 3-4 hrs).

RT

[asudavew]

Originally Posted by dbhansen

Reading other posts (which I should have done earlier ), it seems like 800 degrees may be more reasonable for the oven floor. At that temp, the manufacturer says the 2" board will reach 163 degrees on the outside (at 80 degrees ambient temp). That's more reasonable. Thanks for the input!

Just giving ya a heads up.

I think the insulation boards are the way to go, if you can afford the expense.

Take pics of your build.
We are all voyeurs here!

Dave

[dbhansen]

Dave, links to my pics are in my signature line. I have definitely decided to go with the boards; I just need to decide which ones and how thick!

[asudavew]

Originally Posted by dbhansen

Dave, links to my pics are in my signature line. I have definitely decided to go with the boards; I just need to decide which ones and how thick!

Oh!! I didn't notice the link.

If I had a do over.... 4 inches of board at the minimum....

[asudavew]

These would be great for insulating the hearth.
Check out the 2 lb bricks.


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