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Post by photoman290 on Dec 12, 2014 5:20:03 GMT -8
as some of you know i have height restrictions in my yurt so a "standard" oil drum would be to high to use with a batch rocket. i am thinking of having the rocket stove outside the yurt and using the thermal mass in the yurt. i know this would work,but i would be losing 60% or so of my heat. i am thinking i may be able to recover some of this lost heat by adding a second oil drum on top of the standard one and filling this drum with water,keeping the top open of course.
the plan is to insulate this drum heavily and when the water is up to say 80C transferring it to a second drum inside the yurt. i will use a thermostat set to 80 C to switch on a pump to transfer the water when it is hot enough. still need to do the figures for how long it will take to heat 200ltrs of water to 80c from ambient. hopefully i can keep the batch going long enough to do this. why 80C? that is the max temperature my pump will run at. i could use oil and go for a much higher temperature,but then finding a suitable pump may be a problem, plus water is free.
this is a job for next summer as for this winter i am using my spike type oil burner together with a thermal mass. testing so far seems to working well. just hope i can dry the mass out before spring.
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Post by peterberg on Dec 12, 2014 6:41:25 GMT -8
How high is the yurt in the middle where the heater should be? Possibly a smaller system would fit, something like the height of a cooking range or a little bit more.
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Post by photoman290 on Dec 12, 2014 7:29:05 GMT -8
hi peter,
i know the middle of the yurt is the usual place for the stove in a yurt,but i want to keep the central area clear.
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Post by peterberg on Dec 12, 2014 9:46:06 GMT -8
i know the middle of the yurt is the usual place for the stove in a yurt,but i want to keep the central area clear. OK then, I'll refrase my question. What is the height restriction you need to work with? |
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Post by photoman290 on Dec 12, 2014 10:45:58 GMT -8
sorry, see what you mean now. around 6 foot 6 to the roof assuming i have 2 foot clearance to the wall. the roof slopes at about 25 degrees. i could gain another 4 or 5 inches if i put the burn chamber on the ground rather than the floor. quite happy to do this in the final implementation in the summer.
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Post by shilo on Dec 13, 2014 21:56:22 GMT -8
6 foot?
so what the problem?!
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Post by peterberg on Dec 14, 2014 2:10:34 GMT -8
You could implement a batch rocket in two barrels on top of each other, that would be 5.8 ft high. Alternatively, two barrels side by side with the combustion chamber low in the first one. The second bell connected really low to the first and at the opposite to the vertical chimney. For a 6" system those two barrels wouldn'be enough so I' suggest you scale the batch rocket down to say, 4.5 or 5". That would restrict the length of the riser a bit, probably just enough.
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Post by photoman290 on Dec 14, 2014 3:29:14 GMT -8
shilo,the total height of the yurt is 6 foot 6 to the roof poles. at the moment my cut down oil drum gives me around 2 foot 6 to the nearest roof pole. maximum height the drum could be is around 4 foot from the floor,hence the idea of having it outside. a better way of phrasing the question would be "what is the shortest riser i can get away with"
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Post by peterberg on Dec 14, 2014 6:11:45 GMT -8
a better way of phrasing the question would be "what is the shortest riser i can get away with" Depends on the size of the batch box, i.e. the diameter of the riser. Let's see... the riser is measured from the floor of the firebox, a 6" system would give you a riser of 34.56", a 5" would get you 28.8", a 4.5" would give you 25.92". These are all the shortest options, but some people made the riser even shorter and got away with it. |
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Post by photoman290 on Dec 14, 2014 8:09:07 GMT -8
that sounds doable. 4.5 inch seems a good compromise between something tested and well documented and something getting near the edge of being unstable. i can remove some of the wooden flooring so i can have the burn chamber at floor level that will gain me about 4 inches. from what i have read having a bigger clearance between the riser and the top of the drum is not as critical in a batch? have i got that right?
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Post by peterberg on Dec 14, 2014 8:44:05 GMT -8
Yes. The top gap could be anything from 4" up to 4ft. Maybe even more but that isn't tested yet. I do recommend one foot for a 6" system, so that would be 9" for the 4.5" system. A 55 gallon barrel is 35 inch high and the riser plus insulation underneath would leave you with an 8 inch top gap or there abouts. Close enough, sounds doable to me also. This will give you 3 foot 6 between the roof poles and the top of the barrel.
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Post by shilo on Dec 14, 2014 10:25:56 GMT -8
put reflectiv insulation ander the roof.
try leaning hitrizer (if you have a tall chimney)- peter please correct me
7" is o.k. with 9cm top gap (not ideal) so you can do 5" system with 7cm for sure.
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