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Post by rockitman on Sept 24, 2013 9:32:34 GMT -8
Good evening folks! Been lurking on your forums for a while now, I am considering sticking a rocket mass heater in a 20 metre polytunnel.. I will endeavor to learn Sketchup but for now please forgive my wee drawing (not to scale), I hope you understand it... I like the idea of the half barrel bell system. I'd like to surround that with the soil for growing our veggies in over winter. I'd also like to sink the kernel below the ground to eliminate the heat exchange barrel as I'd like to transfer as much heat as possible into the thermal mass (the soil) I've a couple of questions... Would sinking the kernel below the ground effect the available air needed for proper combustion? Using a bell system like this, do I still need as big a chimney as possible for draw or is it unnecessary? 20 metres - is it dooable? What size of system would you folks recommend...  Would be great to hear back from you all with any pointers Sean  |
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Post by matthewwalker on Sept 24, 2013 10:54:28 GMT -8
Interesting idea Sean. I have no idea how your front end will work, or not, with that configuration. It just might work. As for overall length, I've run 11 half barrels for a system of about 11 meters, and felt it was too long. It worked, but would have been better a bit shorter. Although, without the big radiator at the front end, you might be able to go longer than I did. Good luck man!
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Post by Rinchen on Sept 25, 2013 0:46:34 GMT -8
Hi,
Make sure to have enought soil to buffer the heat, otherwise you will cook the roots of you plants especially in the first which gets the full blast of the heat riser.
Also make sure to test thoroughly before your final installation so you wont get disappointed.
When testing take into account that bare barrels will extract a lot more heat than barrels covered with soil. So cover them with soil to have a representative testing setup.
Good luck!
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Post by rockitman on Sept 25, 2013 1:30:09 GMT -8
Thanks for the suggestions folks Have been having a bit of a ponder about the setup. One other thing I'm planning on putting in is sub irrigation - perforated drainage pipe wrapped in landscaping fabric. The soil will wick out the water, which will be kept topped up by a water butt and ball cock valve... that's the theory at least. If I'm having these pipes running the length of the polytunnel, it might be a lot simpler to use the water running through them as the medium to transfer the heat. No need for a mass excavation for a 20 metre bell! So back to the drawing board. Has anybody done anything similar to this? Having a search on the forums at the moment. Ideally the water wouldn't to get too hot... a slow low heat transfer instead of a big initial blast. |
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Post by PeterG on Sept 25, 2013 2:31:58 GMT -8
I have a polytunnel too and like your idea. Can't really contribute at the mo cos I'm just doing a rocket for the house but I'll watch with interest.
PeterG
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Post by PeterG on Sept 25, 2013 2:38:06 GMT -8
I have a polytunnel too and like your idea. Can't really contribute at the mo cos I'm just doing a rocket for the house but I'll watch with interest. I do think (imho) using water as a transfer medium will be safer and of course if you insulate your storage tank well you have a thermal mass! Why not just circulate the warm water rather than using it to irrigate? PVC pipe buried in the ground with a CH circulating pump on a timer and perhaps a thermostat if you're looking for frost protection? Hmmm, you've got me thinking now, dammit!
PeterG
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Post by rockitman on Sept 25, 2013 3:14:41 GMT -8
I have a polytunnel too and like your idea. Can't really contribute at the mo cos I'm just doing a rocket for the house but I'll watch with interest. I do think (imho) using water as a transfer medium will be safer and of course if you insulate your storage tank well you have a thermal mass! Why not just circulate the warm water rather than using it to irrigate? PVC pipe buried in the ground with a CH circulating pump on a timer and perhaps a thermostat if you're looking for frost protection? Hmmm, you've got me thinking now, dammit! PeterG I like your thinking PeterG! Due to put up a wind turbine and LED lighting system so we should have some leccy for CH pump. I'm also looking into the Jean Pain method of heating water through a big ol' compost mound; could be the best way to go about all this providing I can get a hold of the materials. Which would sadly make the rocket redundant, will just have to build a hot tub instead... |
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Post by PeterG on Sept 25, 2013 4:45:46 GMT -8
Easily distracted then? ;-))
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Post by rockitman on Sept 26, 2013 6:31:16 GMT -8
Easily distracted then? ;-)) Ohh yes, seem to be. Just trying to figure out what's best fit for purpose, it's a shame to be giving up on the rocket approach! Who knows, may revisit it... |
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