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Post by hedley on May 8, 2020 4:00:23 GMT -8
Hi all firstly wow what an informative site and seriously dedicated members.
I have been here lurking for a month or so as a guest and as a member for a week. I'm currently at early stages of design and build of a hot tub, to be started and completed as funds allow, I would like to use a wood fired heater to reduce minimise heating costs, a batch box rocket seems ideal, it would be an open system for heating the water through stainless tube and or tanks that may make up the bell walls. The water directly from the hot tub circulated (pumped).
In reading here I have seen but can't now find a table / spread sheet that shows all the dimension for the core dirrived from cross sectional area of the riser. Can anyone point me back to this?
My head is literally exploding with material considerations for construction. For simplicity and as light a weight as possible I'm looking at secondary air through floor chanel (walker tube?) standard batch box and riser design with removable Bell for the heat transfer to water.
Many thanks Hedley
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Post by hedley on May 8, 2020 4:21:33 GMT -8
Think I've stumbles a Cross it. batchrocket.eu/en/building#dimension:-) Although this is for a p chanel design, I read 25% air being 20% primary and 5% secondary through the p chanel, I'm sure I saw somewhere the floor chanel being 20% total and 10% primary and 10% secondary. Are the core design the same otherwise? I really do not want to reinvent the wheel so a proven core design is a must as my start point. I can then experiment with the bell and heating the water.
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Post by peterberg on May 8, 2020 6:42:43 GMT -8
Although this is for a p chanel design, I read 25% air being 20% primary and 5% secondary through the p chanel, I'm sure I saw somewhere the floor chanel being 20% total and 10% primary and 10% secondary. Are the core design the same otherwise? Hi Hedley, welcome to the boards. The floor channel arrangement is just replacing the p-channel. It's up to the builder which to choose, both will do it's job. In a 150 mm (6") batchrocket the floor channel's vertical stub is very close to the p-channel size csa-wise, the horizontal part called feed is twice as large. In the door there's a combined air inlet of just 25% of a round riser's cross section area again. That said, in my own heater this combined inlet is 20% since there's a very good chimney behind it. This is only logical: air supply is the opening vs air velocity. Better chimney, higher air velocity and therefore smaller opening in order to get the same amount of air inside. I presume you are building the hot tub outside. Wouldn't it be simpler to go for an open core then? No door, no secondary air provision, no rusting steel outside. Just looks like an open fire but in the majority of cases this arrangement is already much more efficient and clean burning as compared to an awful lot of so-called wood stoves. Have a look at batchrocket.eu/en/applications#opensystems
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Post by hedley on May 8, 2020 8:17:31 GMT -8
Thanks peterberg, never expected a reply so quick.
Yes the hot tubs outside, however, in a confinedish space also in time it will be enclosed in a gazebo type structure,
Any metal will likely be stainless as I can source offcuts for free from work, also hoping for best efficiency I can achieve as I have doubts it will be man enough for the task partly because of what I have read here,
It is however supplemental heat to boost the electric element and speed up heating.
I love the aesthetic, the thought of using waste wood which I have in pleantifull supply. The whole idea fires me up
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