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Post by wrekinwanderer on Sept 8, 2013 14:22:06 GMT -8
Okay, another battle of the elements, this time cob versus firebrick.
What I would like to know, more or less, is how much thickness of cob compares to 1" of 42 GD or 80GD Firebricks in terms of radiating and storing heat? Any ideas?
Also, what materials provide the heaviest, densest, mass?
I am wanting to do a small bell, with a footprint of max 50cm2 and perhaps 60cms high. We have good clay soils here, so of course I'm drawn to the cheap option. However, am pressed for space and time so will consider the more expensive firebricks. I want this bell to store the most amount of heat possible and give it out over the longest possible time....
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Post by Donkey on Sept 9, 2013 6:34:53 GMT -8
I don't now that anyone has done that comparison scientifically..
It'll be a little bit of a difficult thing (or at least, rather involved), since no two loads of cob are identical. If you want more thermal mass, add more sand. Many clay types can hold a remarkable amount and still be workable.
Do some tests. First, find out how much sand you can reasonably get in to your clay. When completely dried, weigh them and test them out in a fire. Test them side-by side with your brick, see how hot they get in how much time and how long it takes to cool again.
Come back here, when you've done your tests and let us know how it went!
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Post by talltuk on Sept 9, 2013 11:21:43 GMT -8
Hi. I have just started experimenting with electric storage heater bricks to cobble together a j tube. These store an amazing amount of heat and are about 20 mm thick and around 150x100mm square. Very heavy.
My plan is to use them as an ingle nook fire place for a woodburner when I build our house but I thought they would make excellent mass for a bench or bell, but would need a plate to make the top of the bell.Maybe setting the in cob, so as to provide a core, with the cob supporting.
I get these as a heating engineer and plumber when we remove storage heaters to install radiators. Any engineer would be happy for someone to come and taje them away, they weigh a ton. Each is about 6kg.
These are rough figures as I haven't measured them. I fired my first ever j tube (video to follow) made from them for twenty minutes with a twin wall 100mm flue wrapped with glass fibre insulation for a riser. The bricks were hot enough to boil water straight off
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Post by wrekinwanderer on Sept 10, 2013 11:49:24 GMT -8
Hi Donkey. A challenge! Although don't hold your breath, it may be a while before I come back to you...
Seeing Talltuk's posts makes me wonder how much one of your adobe bricks weighs, do you have any idea?
Mike
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Post by Donkey on Sept 10, 2013 13:50:52 GMT -8
I keep meaning to weigh the things, but haven't.. Dunno.
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