Insulating Board Help Needed

[rbigante]

I was trying to locate insulating board local to the Pittsburgh area and I found this material called Thermo-12. It's made from hydrous calcium silicate. Compared to FB Board: maximum operating temperature is 1200 deg F (FB is 2300 deg F), bulk density is 14.5 (FB is 19), thermal conductivity at approx 400 deg C is 0.65 (FB is 0.5), compressive strength is .69 MPA (FB is 0.5 MPa)I can get it in 3 ft by 1 ft by 2" thick pieces for about 10 bucks per board.

The biggest thing that concerns me is the maximum operating temperature of 1200 deg F. Will the oven reach this??? Will the bottom of the fire brick floor ever reach this???? I was also thinking of a 2-3 inch pad of vermicrete followed by this stuff. help/advise please!!!!!! thanks, Rino

[dbhansen]

Re: Insulating Board Help Needed

Rino, as far as I know, the insulating layer is unlikely to reach those temps. You might see 1200 on the interior surface of the oven when the flames are roaring, but there would be no need for you to saturate the bricks with that much heat, if that were even possible. But 1200 is probably the minimum you'd want, just to be safe.

The thing that catches my eye in the specs for Thermo-12 is that the thermal conductivity rises sharply after 500-600 degrees, but they don't show the numbers after 700. You may want to call the manufacrturer and see if they can recommend Thermo-12 as support for a brick oven. Otherwise, all the numbers look good. You'd also want to make sure it doesn't lose strength when wet (not something you want to discover after your build).

You may not find anyone on this forum that has tried it before, so you may be breaking new ground. Not a bad thing, but there are no guarantees.

[rbigante]

Re: Insulating Board Help Needed

unfortunately, I don't really want to break new ground in this situation. If it doesn't work, I'm not really sure what I'd do (hah hah). probably take a few sticks of dynamite to it all. I couldn't imagine having to start from the insulating hearth again.

I think I'll keep looking or go with the vermicrete. At least that way is proven and not too expensive if I mess it up somehow.

[christo]

Re: Insulating Board Help Needed

Hi Rino,

Not wanting to sound like an advertisement - but I used the FB board. It got to my place quickly and is quite solid. It also made it pretty easy to laydown the floor and get it level - my biggest problem was accounting for the inconsistency in fire brick vs. compensating for a wavy vermicrete layer.

I've been using my oven for over a year now and it performs very well.

Christo

[rbigante]

Re: Insulating Board Help Needed

Any opinions on this stuff:

It's called Super Caltemp Gold 1700 manufactured by IIG. It's made up of lime, silica & reinforcing fibers, no asbestos, extremely low water of hydration. Maximum continuous temp of 1700 deg F, density of 18 pcf, compressive strength of 450 psi!!!!, thermal conductivity at 800 deg F is 0.105 W/m/ deg C.

I don't have a price yet but it's in the works. Looks like this stuff will work. Comes in thicknesses up to 3" thick, in 1' x 3' boards. Any thoughts????