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cjt 04-19-2010 12:59 PM

Hello there, I have finished my oven and tried it out a few times. the floor is fire bricks on top of 2" of castable insulation sat on top of 4" of concrete with a cavity under to provide storage i have noticed after been up to temp for a while the underside of the concrete gets up to 54*C (130f) is this normal ?? seems a lot of heat loss to me. Could i place a sheet of kingspan under the concrete to insulate it ??. I also (like a fool) ! let my 4" concrete oven floor into my blockwork by 1" so when hot i get the tiniest of cracks going 6" down the back wall of the base ! but when cool disappears again am i worrying too much?. Any comments would be appreciated

kebwi 04-20-2010 07:49 AM

Re: insulation
The 2" castable insulation is what? Some sort of vermiculite or perlite concrete (I'm not asking which of the two, I'm asking if that's what it is)?

cjt 04-20-2010 08:09 AM

Re: insulation
yes perlite i think, I was advised to use it by a boiler/ refractory engineer he supplied me with both rescocast, and litewate 600.
Technical Specification Datasheet Level 3
I hope thats some use thanks for your reply

GianniFocaccia 04-20-2010 08:14 AM

Re: insulation
CJT's insulation layer may be vermicrete, but there are a number of castable insulation products available like Versaflow or Kast-o-lite which are manufactured by Harbison-Walker. These are designed to work at 2600F - 3000F and rely on the chemically-created air pockets inside the cured refractory concrete to work.

david s 04-20-2010 08:24 AM

Re: insulation
If your oven is new it is most likely that there is still quite a deal of moisture trapped in under the floor. Because heat rises iy takes a long time to get this moisture out. The remedy is to just keep firing. You should find that the more ypu use your oven the less heat will penetate through the floor, as wet insulation doesnt work well. Two inches of insulation is less than that recommended. Keep cooking.

kebwi 04-20-2010 08:48 AM

Re: insulation
My thought, as reflected by david s is that 2" vermicrete/perlcrete is a bit on the shy side. Insulating "boards" of various types are often used at that thickness but such materials have greater insulative power than vermicrete and perlcrete. I used 3" of board myself (InsBlock 19).

You're probably okay though, keep drying it out.

GianniFocaccia 04-20-2010 11:06 AM

Re: insulation
Thanks for the spec sheet. I'm wondering, did your refractory engineer advisor specify 2" thickness? How many pounds of material did it take to get that 2" thickness? You wouldn't have any pics of it would you?

cjt 04-20-2010 03:53 PM

Re: insulation
I could kick myself now, 2 20 kg bags if i remember (88lb) It all is a bit of a blur now i wish i had written more stuff down. Im working on some pictures, need to reduce there size as they are too big @ moment to load !

cjt 04-20-2010 04:13 PM

Re: insulation
Although, tonight had another fire grilled some sausage and batch cooked a load of meatballs and now just taken some bread out which looks and smells fantastic (should i be doing this on a week night ?!!!)

GianniFocaccia 04-21-2010 05:17 AM

Re: insulation
Man, I'm hungry! Can't wait to see the pics.

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