Which calcium silicate board?

[Andrew Beal]

I am in the process of building up my hearth. I have a concrete slab poured. I have about 80mm on top of the slab to play with that I can add insulation over. I was planning to put down calcium silicate board as mentioned in other posts. Then 3:1 vermiculite cement over the top then my firebricks.

I am trying to find some board but the only stuff I can find is only rated to a 90 degrees celsius working temperature. It is supalux brand and is pretty dense (875kg/m3), and water resistant. Is this the right board to use? 90 degrees seems pretty low temp to me. What temp range do I need?

Initally I bought some 25mm kaowool ceramic board rated to 1400 degrees but am dissapointed as it is very soft (200 kg/m3) and It looks like it will absorb moisture. Im not sure if its suitable to put the weight of the firebricks on.

[kebwi]

May I ask how you decided on 3:1? I don't think I've ever seen that written anywhere? I thought most recipes started at 4:1 and went up from there.

I used InsBlock 19 board, which has lower temperature tolerance than the other kinds of boards, but is high enough for an oven (I don't think it can be used to directly line a kiln or forge for example).

I have no idea if you can get it in NZ though.

[Johnny the oven man]

Originally Posted by Andrew Beal

I am in the process of building up my hearth. I have a concrete slab poured. I have about 80mm on top of the slab to play with that I can add insulation over. I was planning to put down calcium silicate board as mentioned in other posts. Then 3:1 vermiculite cement over the top then my firebricks.

I am trying to find some board but the only stuff I can find is only rated to a 90 degrees celsius working temperature. It is supalux brand and is pretty dense (875kg/m3), and water resistant. Is this the right board to use? 90 degrees seems pretty low temp to me. What temp range do I need?

Initally I bought some 25mm kaowool ceramic board rated to 1400 degrees but am dissapointed as it is very soft (200 kg/m3) and It looks like it will absorb moisture. Im not sure if its suitable to put the weight of the firebricks on.

Go and see your local Pyrotek agent they should have it. The brand we have in Aus. is Skamol

[Andrew Beal]

Thanks for the info. Ill keep looking but Im having trouble finding any board in NZ other than the kaowool. I might have to use vermiculite concrete for the whole hearth 4:1 as stated.
I found this thread about using the kaowool board. Looks likes its no good at all. Pity Ive got three sheets of it...

http://www.fornobravo.com/forum/f6/k...oard-2588.html (Kaowool Refractory Ceramic Fiber Insulating Board)

[Johnny the oven man]

You have a refractory company in NZ that may be able to sell you some, try Andreco-Hurll.

[DWC]

I have just brought some calcium silicate board from the Crow Refractory, 20 McLaughlins Road, Wiri, phone: 09 278 2005. Very helpful and also stocks ceramic blanket.

[Swampy]

Certec in auckland sell the insulating blanket for $30 per meter(600mm width)or 7.6 meters for $150.They also sell the board but im not sure on the price.

ph 09 8202240

[Johnny the oven man]

Heck you guys get ripped off in NZ. We sell blanket from $75/7.2m roll.