jorgeenelpueblo
New Member
Learning before building the first heater.
Posts: 11
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Post by jorgeenelpueblo on Dec 4, 2016 14:45:16 GMT -8
Hi all, Mr. Van Den Berg, thanks for the time spent developing and making public the batchbox. As suggested on your webpage, I downloaded the video of "building a cobbed RMH" (that I have not managed to end watching, by the way, no time yet) and here I am trying to find all the answers before bulding the first one.
Something I am not sure and I have not seen anywhere: If I am limited by existing chimney of 3", Am I really forced to go to a 3" bb system?
And if it is so (as I imagine it will be) How can I do for a longer firebox? 20 cm seems to short to have the wood cut at that length. What other parameters should I adjust? Would it be enough a longer heat riser?
And another extra question, about cement between bricks in the heat riser and in the firebox: How much (ot how little) should I lay between bricks?
Thanks in advance for any answer to this my first question,
Jorge
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Post by satamax on Dec 5, 2016 3:43:14 GMT -8
Jorge, i think 4 inch is a realistic limit. IIRC, there's somebody who has made a 3" here. Do a search.
What does limit you to 3"?
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Post by drooster on Dec 5, 2016 9:30:18 GMT -8
... If I am limited by existing chimney of 3", Am I really forced to go to a 3" bb system? Do you really have a 3" diameter chimney?
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jorgeenelpueblo
New Member
Learning before building the first heater.
Posts: 11
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Post by jorgeenelpueblo on Dec 5, 2016 15:22:34 GMT -8
... If I am limited by existing chimney of 3", Am I really forced to go to a 3" bb system? Do you really have a 3" diameter chimney? In our current living room there is an existing metal exhaust pipe that has 3 " diameter, yes. That place had a toilet before and I believe this ppe was its ventilation. And it connects to the outside, through the roof, goes out like 1m in a chimney that is also used for a kitchen exhaust fan. We used to have an old diesel boiler exhausting through that chimey 30 years ago, and it warmed nicely the bathroom in the third floor. It is a small room, on a first floor supported by very old wooden beams, so I can not put a very heavy heater anyway. Actually, the whole house is more than 200 years old and there is no way to know what has been built when. There is a gas-based central heating, cast iron radiators, and no real good place to install a big heater that could replace it so I am thinking in building 3 or 4 small bb and somehow link the existing radiators to the mass warmed by the bb. The question of the CSA of the chimney is something I have not read elsewhere. I would imagine it has to be at least the same as the CSA of the heat riser. Anyway I will follow the suggestion of Satamax and search for existing 3" bb
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Post by peterberg on Dec 6, 2016 2:26:30 GMT -8
That pipe that is used to vent a toilet, how do you know it is fit to use as an exhaust chimney? In 99% of cases a ventilation shaft isn't the same as a chimney stack for hot gases. Moreover, when it is sharing the same stack with the kitchen fan, there's a fat chance that the heater will blow back when cooking is going on.
Too much risk to my taste, please look into other possibilities. And quite separated, I know for sure a 4" batch box will work as long as it is built out of insulating materials or split firebrick and insulated from the outside. Regular firebrick isn't isn't insulative enough. I know about the results of a 2" batch box built out of insulating firebricks and it worked only 1/4 of the time and getting it to clean burning was a pain. Whether or not a 3" BBR would work satisfactorily is open for denate as far as I am concerned.
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jrl
Junior Member
Posts: 101
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Post by jrl on Dec 9, 2016 6:37:46 GMT -8
That pipe that is used to vent a toilet, how do you know it is fit to use as an exhaust chimney? In 99% of cases a ventilation shaft isn't the same as a chimney stack for hot gases. Moreover, when it is sharing the same stack with the kitchen fan, there's a fat chance that the heater will blow back when cooking is going on. Too much risk to my taste, please look into other possibilities. And quite separated, I know for sure a 4" batch box will work as long as it is built out of insulating materials or split firebrick and insulated from the outside. Regular firebrick isn't isn't insulative enough. I know about the results of a 2" batch box built out of insulating firebricks and it worked only 1/4 of the time and getting it to clean burning was a pain. Whether or not a 3" BBR would work satisfactorily is open for denate as far as I am concerned. That pipe could be the ventilation for a septic system or dry well, where you said it was once connected to a toilet. Light a fire in it and boom! Methane gas rocketing from the roofline! Gives a whole new meaning to a P-Channel!
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jorgeenelpueblo
New Member
Learning before building the first heater.
Posts: 11
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Post by jorgeenelpueblo on Dec 10, 2016 14:53:57 GMT -8
No risk of methane, the pipe is just going up. But I had not thought about the blowing from the kitchen fan, so I am glad I started with the basic questions before elaborating any further on my mind. I just thougth that it is metal pipe and that temperatures should not be that high, so it would have been ok. So for the time being, this place falls out of the list of heaters-to-build.
I guess I will start by a basic 4" setup replacing a currently-working open fire, which has good draft already and an individual chimney, and learn first before experimenting.
Thanks guys,
Jorge
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