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Post by chrisor on Jan 22, 2015 14:04:11 GMT
I've been given some tiles,concrete balcony tiles.
I was wondering if they would be suitable for under a fire brick hearth. They are 22 mm thick,there's enough for 2 layers,if that's even possible ?
There's lots of data I don't understand
Dry density approx 1600 kg/m3
Flexiral strength 3 N/mm2
Most importantly the thermal conductivity is 0.79 W/mk
I don't understand any of that to be honest,can any resident experts please advise me whether or not they would be suitable ?
Cheers !
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Post by chrisor on Jan 22, 2015 14:32:17 GMT
Maybe I should add,the tiles are aquapanel tiles.
Thanks.
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Post by kstronach on Jan 22, 2015 18:09:53 GMT
well i'm no expert but i'll have a crack!
weren't you planning to use thermalights and calsil board under your floor? or are you thinking of trying to use these instead? if you are, i wouldn't bother and would steer clear of those mate to be honest, i don't really understand the figures either but what you want under the floor is some decent insulation, its arguably the most important part of the oven to get right. you've got a few different options though on how you go about it, you could go for about 4" of vermicrete (vermiculite mixed with cement at around 5 or 6 to 1 for under the floor off the top of my head) or a lot of people go for thermalight blocks which are probably the easiest method or calsil board which i don't know a lot about sorry. if i were you i'd stick to your original plan!!
keith
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Post by chrisor on Jan 22, 2015 18:43:22 GMT
Was gonna use them cos they were free,I'll stick to the original plan if you think that would be better.
Cheers for the advice pal.
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Post by kstronach on Jan 22, 2015 19:07:11 GMT
yea definitely! its the one part of the oven you need to get right first time as you can't change it after! if you wanted to cut the cost a little you could do away with the cal sil board and just use the thermalights?
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Post by chrisor on Jan 23, 2015 16:11:22 GMT
Cheers for that.
Would using cal sil and thermalights be over the top and wasteful,or is it more the merrier,as I suspect ? I imagined laying fire bricks on a cal sil board would give me a good surface to get them level.
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simon
valid member
Posts: 33 
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Post by simon on Jan 24, 2015 14:05:45 GMT
The mantra tends to be that you can't have too much insulation. There comes a point of diminishing returns, but thermolites are not expensive, so why not?
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Post by cobblerdave on Jan 24, 2015 22:22:22 GMT
G'day
The excepted standard for insulation for the hearth seems to be 50 mm of cal sil or ceramic board. 100 mm of pearlite/cement will provide the same level of insulation.
But thermalite block (ACB) i dont know of a standard.
Ive got 50mm of Hebel brand ACB as hearth insulation. Im happy with the performance of my oven and it doesn't seem to differ from others that I read about. But I do find after 24 hrs the underside of the slab is slightly warm.
So I suspect perhaps it should be 75 mm to 100 mm thick would be best
Regards dave
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Post by chas on Jan 25, 2015 9:05:29 GMT
All as above... this question is pretty well where I started last year, and though hell-bent on a design I'd established, I was gently persuaded that I should go for insulation as well as mass in the floor - I was able to incorporate a vermicrete layer with only minor adjustment to the plan.
Look at it this way - cos it's very real and ahead of you - imagine your first 'burns', the anticipation of those bakes... and through a bit of hastiness now, you can't maintain temperature. You can probably get more insulation over the dome, but retro-fitting the slab is a pain.
Keep us posted!
Chas
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