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Post by moskvach on Dec 14, 2017 5:55:01 GMT -8
Hello . I am sory for my english language . I dont understand how calculate ISA for the bell / batchbox . I see Batch Box Dimensions Calculator , ratio 1:1,77 - how it use . thanks
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Post by wiscojames on Dec 14, 2017 6:11:39 GMT -8
Calculate the surface area of the walls and ceiling (pillars if any) of the bell. Don't add the surface area of the floor. ("how to calculate" "how it is used")
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Post by Orange on Dec 14, 2017 6:39:35 GMT -8
Riser diameter / Internal Surface area 12.5 cm (5") ISA 3.7 m² (39.8 sq ft) 15.0 cm (6") ISA 5.3 m² (57 sq ft) 17.5 cm (7") ISA 7.2 m² (77.5 sq ft) 20.0 cm (8") ISA 9.4 m² (101 sq ft) 22.5 cm (9") ISA 11.4 m² (123 sq ft) 25.0 cm (10") ISA 14.7 m² (158 sq ft) batchrocket.eu/en/building
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Post by moskvach on Dec 14, 2017 7:28:16 GMT -8
I read this page batchrocket.eu/en/building . If we have riser diameter 30sm the ISA will be ....? I dont understand how calculate ISA if riser diameter 18sm, 19, or 28 . How calculate internal surface area of any riser diameter . May be i cant translate some terms (automatic translater is ugly).
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Post by moskvach on Dec 14, 2017 8:05:05 GMT -8
I mean the internal surface area with that the stove will be work well . Ratio between size of batch box and surface area . Thanks
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Post by peterberg on Dec 14, 2017 13:28:51 GMT -8
The ISA through all the batch box sizes isn't linear but exponentional instead, so I tied it to the cross section area of the riser. A 15 cm diameter riser's csa is 177 cm², the ISA which can be served by such a system is 5.3 m². That's one point we are sure about, although it is a quite conservative figure.
Another one where we are sure about is the ISA of a 20 cm system, this is 9.4 m². Csa of the riser is here 314 cm², accidentally 177% of the 15 cm system. What we do is comparing how much larger or smaller the csa of the riser is, compared to the 15 cm system. This is another sure point, checked and approved.
You are asking for the ISA of a 30 cm system. Riser csa of such a system is 707 cm², 707 / 177 = 3.99. So the ISA of a 30 cm system could be 3.99 times that of a 15 cm system which is a little bit more than 21 m².
The same goes for any other size, the csa for a 19 cm system would be 283.5 cm², divided by the 177 cm² of the 15 cm system you'll get 1.6. So the bell of a 19 cm system could be as large as 5.3 x 1.6 = 8.48 m² ISA.
All the internal surfaces of the bell need to be calculated, except the floor and the firebox. And of course surfaces that are insulated at the inside of the bell. Even when the top surface is insulated at the outside the inside will extract heat so it need to be in the calculation. The riser csa need to be calculated as if it is circular. So a riser which is 15 cm square isn't any larger compared to a circular one of 15 cm diameter, aerodynamically speaking.
Up till now it works, I calculated a number of systems and they were all correct. Any larger would work provided a bypass is installed but I don't like bypasses. It feels like a stop gap to compensate for a possible sloppy design to me.
Not to say all heaters with bypasses are sloppy designs, far from it.
I hope your automatic translator will be capable enough to translate the above text.
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Post by moskvach on Dec 15, 2017 3:06:24 GMT -8
Thank you very mach Peterberg !!!!!! Now i all understand . I love this forum !
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Post by Orange on Dec 15, 2017 4:20:31 GMT -8
here's an updated BB calculator link
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Post by moskvach on Dec 15, 2017 4:57:02 GMT -8
Thanks Orange . This is whas that i needed.
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