morticcio
Full Member
"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
Posts: 371
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Post by morticcio on Nov 7, 2013 6:35:31 GMT -8
What material is best to use for capping the top of the bell - refractory castable or firebrick? The outer measurements are 610mm x 1150mm. If I use refractory castable - what is the minimum thickness and the approx. area a 25kg bag of 1600C castable will cover for that thickness so I can work out how many bags I'll need? I can source 610mm x 230mm x 76mm firebrick but it will work out expensive!
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Post by peterberg on Nov 7, 2013 10:30:48 GMT -8
The 1600C is probably over-specced. You need two slabs to span that stove, both can rest on three sides that way. Minumum thickness 50 mm, cover with isulation.
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morticcio
Full Member
"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
Posts: 371
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Post by morticcio on Nov 8, 2013 3:14:37 GMT -8
Thanks Peter :-)
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Post by lincsoldbird on Nov 10, 2013 11:14:22 GMT -8
Peter Why do the slabs need to be insulated?
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Post by peterberg on Nov 10, 2013 12:26:01 GMT -8
It will become the hottest part of the whole stove. Nobody lives against the ceiling above the stove so that part is best insulated. That way, more od the heat will come out at the sides, where we are.
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Post by lincsoldbird on Nov 10, 2013 14:19:06 GMT -8
Thanks
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Post by daniel on Nov 3, 2015 1:21:16 GMT -8
The 1600C is probably over-specced. You need two slabs to span that stove, both can rest on three sides that way. Minumum thickness 50 mm, cover with isulation. I have to cap the heater and have casted 3 slabs ( I needed 4 but I did not have enough refractory) they are 28x75x8cm the span across the top is 62.5cm which are not supported do I need some kind of angle iron to make sure these slabs will not crack and fall, will the angle iron buckle to heat?
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Post by daniel on Nov 3, 2015 1:27:06 GMT -8
Hi,
I posted my question about capping the heater above and I want to mention that the short side of the span is 75 cm on the outside and 62.5 inside, I need a fourth slab which I don't have but I was thinking to put firebricks laying on one side on the wall and the other on angle Iron, will the angle Iron hold?
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Post by daniel on Nov 3, 2015 13:20:34 GMT -8
Ok I ended up putting some angle iron underneath the slabs just to make sure, I needed one more slab so I used firebrick, I probably should have done that from the beginning, it was a pain to put those slabs up by myself. The slabs lay on graphite covered ceramic material and I stuffed some rockwool between them and covered with clay, I will follow with some additional layers perhaps insulation or some heat recovery system.
Today I lit the batch box which was just completed, It works great, I put only a little wood, pine and it works great, I wonder how it will work when the door will be installed and with well seasoned wood, it will be a rocket. The upper firebrick on edge part got hot, in the upper portions you could not keep your hand on. After the fire was gone I closed the chimney exit ( it can not close completely as a safety measure).
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morticcio
Full Member
"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
Posts: 371
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Post by morticcio on Nov 3, 2015 15:04:02 GMT -8
An inverted T-bar would be better. Fit this at the opposite end to the riser. Stick some ceramic fibre paper around the bar to protect the metal and allow for expansion.
Edit - Hadn't refreshed page before I pressed Post so didn't notice you'd already posted a response.
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Post by craypappy on Sept 7, 2017 12:47:15 GMT -8
The 1600C is probably over-specced. You need two slabs to span that stove, both can rest on three sides that way. Minumum thickness 50 mm, cover with isulation. How wide will 50mm thickness safely span across top of bell? Wondering how to avoid disaster of it fails? What type of insulation do you recommend? I see this is an old post. Have recommendations changed?
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Post by Jura on Sept 8, 2017 7:45:27 GMT -8
The 1600C is probably over-specced. You need two slabs to span that stove, both can rest on three sides that way. Minumum thickness 50 mm, cover with isulation. How wide will 50mm thickness safely span across top of bell? Wondering how to avoid disaster of it fails? What type of insulation do you recommend? I see this is an old post. Have recommendations changed? I'm also pondering over the issue at the moment. I found a chamotte slab offer ((50 cm x 100cm x 3 cm)for 25€ ) that would perfectly suit my needs (97 cm is the space i need to have capped) and it's the thickness that makes me a bit anxious about using them. The seller ensures me about the product perfect thermal shock properties but I'm hesitating anyway.
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Post by pinhead on Sept 11, 2017 7:08:12 GMT -8
What material is best to use for capping the top of the bell - refractory castable or firebrick? The outer measurements are 610mm x 1150mm. If I use refractory castable - what is the minimum thickness and the approx. area a 25kg bag of 1600C castable will cover for that thickness so I can work out how many bags I'll need? I can source 610mm x 230mm x 76mm firebrick but it will work out expensive! Is the roof of the bell above the heat riser? Or are you utilizing the classic "barrel" heat exchange above the riser channeling down to the bell? If you're using the latter design, simple materials will suffice - I used classic cob supported with corrugated steel.
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Post by craypappy on Sept 13, 2017 16:39:30 GMT -8
What material is best to use for capping the top of the bell - refractory castable or firebrick? The outer measurements are 610mm x 1150mm. If I use refractory castable - what is the minimum thickness and the approx. area a 25kg bag of 1600C castable will cover for that thickness so I can work out how many bags I'll need? I can source 610mm x 230mm x 76mm firebrick but it will work out expensive! Is the roof of the bell above the heat riser? Or are you utilizing the classic "barrel" heat exchange above the riser channeling down to the bell? If you're using the latter design, simple materials will suffice - I used classic cob supported with corrugated steel. Speaking for myself, roof of bell is above the riser. I'm planning to use castable refractory. Will probably go with 80mm thick slab for peace of mind (Peter above says 50mm is sufficient). I would feel even better if I could add some support underneath but what will withstand the heat? My fear is if slab fails and falls into void, my house will burn down. Am I being paranoid?
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grga
Junior Member
Posts: 76
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Post by grga on Sept 14, 2017 11:54:10 GMT -8
What if you use castable refractory reinforced with regular iron rods (wires), I know the problem of different temperature expansion but I guess that if using 3 or 4 mm wires this should not be critical - Do you agree?. Or to be on a safe side you can cover 10 mm rods with some material (maybe regular paper or pvc foil) to allow expansion this should also add some strength to castable. Or simply fist of 1mm wire cut at 3cm length or better some metal clips mixed in concrete. Would any of this be a good idea?
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