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Post by talltuk on Jul 22, 2014 5:58:09 GMT -8
Hi guys
any suggestions for how to top off a brick built batch box?
I have seen most people doing arches, which is doable but a little skillful for my amateur brick laying talents.
Peter has suggested refractory slab but money is tight and I dont have the room to cast one.
I thought of metal but no air to cool it so it wouldn't last long, and it would probably warp. What am I missing?
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Post by matthewwalker on Jul 22, 2014 7:00:45 GMT -8
Pottery supply shops will have kiln shelves, which will work great. If you are lucky, perhaps you can find an offcut, broken piece, or dismantled kiln somewhere you can salvage from. Do you have any friends who are potters? My neighbor is, and he always seems to have shelf pieces lying around.
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Post by talltuk on Jul 22, 2014 9:51:16 GMT -8
Oh nice one. I will have to have a search. Not sure if I have any locally but worth a try
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jrl
Junior Member
Posts: 101
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Post by jrl on Jul 22, 2014 12:05:43 GMT -8
Hi guys any suggestions for how to top off a brick built batch box? I have seen most people doing arches, which is doable but a little skillful for my amateur brick laying talents. Peter has suggested refractory slab but money is tight and I dont have the room to cast one. I thought of metal but no air to cool it so it wouldn't last long, and it would probably warp. What am I missing? What size system are you building? In my case, the Peterberg dimensions for a 5" system were such that the batch box's width was less than 1 brick's length. This allowed me to span the batch box's width with regular fire brick. No arches or castings required.
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Post by talltuk on Jul 22, 2014 14:22:58 GMT -8
One is going to be 100mm the other 150mm.
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morticcio
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"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
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Post by morticcio on Jul 23, 2014 11:45:45 GMT -8
This is a critical part of the heater. You don't have to cast the slab in one piece - divide it into three or four.
I did some pricing, firebrick versus refractory castable, for the top of my bell. It was cheaper using refractory castable. In the end I found a pizza oven base that fitted perfectly in the skip at local refractory supplier!
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Post by talltuk on Jul 23, 2014 12:50:42 GMT -8
The words local, refactory and aupplier don't really go together here in Norfolk. The kiln shelf seems like a good plan. Casting I just don't have the space for, yet. How long does refactory take to go off?
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morticcio
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"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
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Post by morticcio on Jul 23, 2014 13:37:28 GMT -8
I got refractory castable from my local branch of SIG Insulation (formerly Sheffield Insulations). They had to order it from another branch but it was cheaper than other suppliers. They have a branch in Norwich.
I waited 24 hrs before trying out my batch box. I followed Peter's advice and started with a small fire and gradually built up the heat. Surprising how much steam comes off.
Peter, would a 25mm thick vermiculite or refractory fibre board be suitable for a cap on a bell? If so, would this count towards the ISA if it is an insulating material?
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Post by talltuk on Jul 23, 2014 13:50:49 GMT -8
Sig can get castable? Thats surprising. They are agents of thermsl ceramics though so not out of this world. Need to go snd see them to discuss refactory shapes and vfcf tubes so worth asking.
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morticcio
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"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
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Post by morticcio on Jul 23, 2014 14:13:34 GMT -8
They do Tri-Mor Monolithic Refractories. Not sure if all would be in stock but here is a link.
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jrl
Junior Member
Posts: 101
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Post by jrl on Jul 23, 2014 19:00:18 GMT -8
My 5" system required 6 firebrick for the batch box top. $1.85 / firebrick = $11.00 USD, plus some small portion of the refractory cement I had to buy anyway. Castable refractory 25lb tub = $51.69 on Amazon. I have to imagine the stuff costs a bit more than regular refractory cement, and regular was $55 for 50lb at a local masonry supplier. I think you would definitely need at least 50lb of castable to do the job. Understood this comparison is only relevant for your 100mm system.
Greater than the length of a single fire brick and your casting I guess. How about stone? Anyone done that for a batch box top?
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Post by peterberg on Jul 24, 2014 1:53:58 GMT -8
Peter, would a 25mm thick vermiculite or refractory fibre board be suitable for a cap on a bell? Yes, I suppose it could be done. Two things to consider, though. This stuff is brittle so don't poke the ceiling of the firebox with a piece of fuel. Second, it's lightweight as well so you have to put something on top to keep it down, a large paver for example. If so, would this count towards the ISA if it is an insulating material? I never included the outside of the firebox into the calculation, because it's going to be very hot by itself. The paver on top is different as it is insulated from the firebox top, so this would count as ISA.
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Post by talltuk on Jul 24, 2014 14:05:24 GMT -8
I am loving Thermal Ceramics at the moment. Its a one stop shop. Need to sit down with the local SIG high temp manager and see what we can find out about prices
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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 Jul 24, 2014 23:16:50 GMT -8
I misread this thread - I thought you meant capping the bell not the firebox, hence my comment on the ISA. Apologies for any confusion!
That said, a refractory slab is probably easier and the most durable. Chances are you need to use it for the cap on the bell anyway so you may as well get used to working with it.
I got Superwool HT from SIG too. Just make sure you get the trade prices.
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Post by talltuk on Jul 25, 2014 13:55:30 GMT -8
Lol I did wonder where that was coming from. No bells here. Doing one 100mm brick built boiler, using a metal plate to top the channel from top of riser to downdraught channel, and 150mm with a barrel setup. Both are going outside. The 150 is to heat my shed or a small bench, but also provide a test bed for water heating. As I said, I just dont have the space to cast anything, mores the pity. I live in the city with a tiny urban garden and my new shed is full of scrap copper, reclaimed timber and plumbing tools.
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