phil
New Member
Posts: 2
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Post by phil on Feb 11, 2011 2:00:42 GMT -8
I'm still trying to wrap my head around Rocket Heaters and hope to buy the book soon, but in the mean time had a question:
What kind of variables effect the maximum length of the horizontal flue running through the thermal mass?
The reason I ask, I'm working on a straw-bale home design and trying to figure out if it is possible to create a ~30ft TM bench running the length of 2 140sq-ft bedrooms before venting the exhaust into a vertical flue pipe.
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Post by northriver on Feb 11, 2011 7:15:48 GMT -8
I just finished building a RMH with an 8" flue and had much the same question ... I did not find much in the way of a definitive answer to this question. I limited the combined total length of the horizontal heat exchange pipe and the vertical flue to 30'. Everything seems to be working fine at this length. Having said that I have seen RMH's described on the internet that had longer runs of exhaust pipe. My thought on limiting the length of pipe was to ensure hot enough exhaust gas such that the temperature difference between the bottom and top of the vertical flue would ensure that the chimney worked (hopefully without a lot of percipitation of flue gas). The proposed rocket mass heater code (found at www.ErnieAndErica.info/rocketmassheaterpermitting) uses a longer length if I remember correctly. |
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Post by Donkey on Feb 11, 2011 9:23:43 GMT -8
Quoted from Ernie and Ericha's permitting page:
"Total ducting length from manifold to exhaust outlet may be up to 60 feet, with 30 to 50 feet being typical. NOTE: Some configurations within this range may require special design consideration to ensure proper exhaust."
I think that you don't want much more than 40 feet for an 8" stove and 25 feet for a 6" stove.. I could be wrong, it could be longer for each, though personally I'd prefer not to bump too close to the limits. Better to have breathing room.
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