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exceptional flue length in a rocket mass heater

 
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Hello from country Victoria, Australia.
I'm a hesistant newbie, not wanting to waste people's time.  I have spent many interested hours following threads on rocket mass heaters. I'm keenly interested and delighted to find a forum in which people help one another out. Anyway I have looked for answers concerning my flue dilemma without success, so if you can help I'd really appreciate it
Back story
I've been living in a  square based pyramid, for over 10 years. The envelope is well insulated, underfloor included. Inside the pyramid is pretty much open plan,: 8m x 8m (26'x 26'). A mezzanine ceiling (8' from the floor) extends from the south face to the centre of the structure. The current wood heater is adequate to heat the house - at least after it's been running for a couple of hours. Cutting to the chase, there's no thermal mass in the house and winter mornings are chilly inside. Extending the mezzanine would solve my problem but aesthetically and from the perspective of light loss, it's not an option I'm keen on.
So, wish I could have been shorter to get to the point but will a rocket mass heater function properly if the already cooling gases have to find their way 9 metres or 30' up an ever cooler pipe?
 
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Location: Wellington, New Zealand
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The chimney is the engine of a rocket stove. The taller the stronger the pull on the fire.
 
pollinator
Posts: 289
Location: Penticton, Canada
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building woodworking rocket stoves
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Welcome Jeremy,     I can't quite seem to wrap my head around what exactly your looking for. There are a lot of details left out that would make it easier to help you. Size of heater, is it a pipe or bell heat extraction, batch box or J tube...etc. Pictures would help out greatly too.  
 
JEREMY FOURNIER
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I tried uploading a pic and a sketch - didn't succeed so I'll try again. Don't know at this stage whether to go for a bell or a ducted flue.
 
JEREMY FOURNIER
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I've uploaded a pic of the pyramid from outside and a sketch showing the flue run.
Filename: line-sketch-flue-run.pdf
File size: 182 Kbytes
exterior-house-pic-permies.JPG
[Thumbnail for exterior-house-pic-permies.JPG]
 
gardener
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Location: latitude 47 N.W. montana zone 6A
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cat pig rocket stoves
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Hi Jeremy;  Welcome to permies.

From your picture it looks like your 30 ' rise is all indoors ?  
If so, then you are fine. It will work with no issues.
Outdoor chimneys need to be insulated.
RMH's do need time to properly heat their mass. Once dry and warm they will hold their heat 12 - 24 hrs.
Do you have a copy of the RMH builders guide ?

We would need more details of your plans on design / mass to offer options for you.



 
 
Gerry Parent
pollinator
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Location: Penticton, Canada
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building woodworking rocket stoves
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JEREMY FOURNIER wrote:..... will a rocket mass heater function properly if the already cooling gases have to find their way 9 metres or 30' up an ever cooler pipe?



Rocket mass heaters are known for having much cooler exhaust temperatures than conventional stoves and still exhaust properly if not too cool. "Too" being relative to how much heat you extract via your barrel and/or mass. Around 140-170F is about a minimum temperature range you need to be at to avoid condensation problems and/or stall out the system from lack of draw. There are formulas for figuring this out to determine length of horizontal pipe or internal surface area needed in a bell to come to produce a working system that should meet the minimum temperature requirements.
Something similar to your house design is the RMH in their tipi at Wheaton labs RMH Tipi
 
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