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Rocket Mass Heater for Work Shop, northwestern Ontario Canada

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Hey folks,
I'm new to this site and it looks like a great resource here!
I have a roughly 22' by 24' two car garage converted to a wood working shop that I work from year round. Looking at putting together a Rocket Mass Heater over the next couple of weeks and looking for advice.
I have a 45 gallon metal barrel that will be used in the project and am looking at building roughly a 6 foot by 3 foot by 3 foot unit to run piping through for the "Mass" part of the system using flexible 4" by 4' sections of metal tubing and using sand as the filler.
I'm new to Rocket Mass Heaters and am looking for tips, advice, links etc. I was using a pellet stove to heat the space last year but want to convert to Rocket Mass Heater as I have a pretty much endless supply of wood to use.
Any and all help greatly appreciated. Winter temperatures here will hit minus 40 degrees and below.

Cheers... Joe
Posts: 3124
Location: Upstate NY, zone 5
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A 4" diameter system is very tricky to get working well - most who have tried it have failed. Also, flexible duct of any size will add greatly to the drag and may stall an otherwise well-sized system. It is advised to build a 6" or 8" diameter system at least for your first RMH... then you can experiment after you have a successful standard build.
Have you gotten "the book" - Rocket Mass Heaters (third edition) by Ianto Evans and Leslie Jackson? This will give you all the basic information you need and help you avoid mistakes.
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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JoeO Woodshop ! Welcome to Permies.com, our sister site, and a Big Welcome to the Rocket and Wood stove Forum Threads !

Here is a second to Glen Herberts excellent Thread Extension ! If you were successful in creating a working 4'' system you would find it a little small
for your needs, with a very well sealed Garage Door(s) openings, the 6'' rocket is sufficient for your needs! however only 40% of the heat is prompt
heat that comes off of the barrel, the rest of the heat needs to be allowed to run through the thermal mass giving up its heat energy along the way!
Then it will take at least a couple of hours or more depending on construction for the heat energy to travel through the thermal mass to reach the
thermal masses radiating surfaces to give off the heat energy !

Because there is insulating air trapped between each and every grain of sand, back filling your Thermal bed with sand will S-l-o-w the transport of
heat through the Thermal mass. Largish stones, the size of an egg are a much better medium for heat transfer due to the larger Air pockets allowing
for heat transfer by convection! Better still is the conventional build with a clay mortar usually called cob,and lots of very dense rock for backfill and
the careful elimination of any air pockets, this will speed up the transfer of heat through itself. The deeper the horizontal pipe is placed within the
thermal mass the more heat energy will be stored! the shallower it is placed within the core, the faster it will warm through and start warming your
work space with radiant heat ! This is heat that warms the objects it hits and not the air a further saving of heat energy !

Short version 40% is prompt heat, the other 60% will continue to heat this space for hours after the fire goes out, which is better than a very efficient
wood burner that still dumps its heat out of doors !

While you might find a second hand older edition copy of Rocket Mass Heaters via Amazon Books, or Alibris Books, I can highly recommend the
Brand New 3rd edition, direct from Evans and Jackson At Rocketstoves.com , and recommend the Downloaded PDF copy that lets you be the
printer of as many copies as you can actually use ! One Low price, and if you are familiar with PDFs- puts the information immediately into your hand !

This book will quickly allow you to talk with your fellow members here at Permies.com knowing that you will be using the same simple terms to describe
the Size(s), Shape(s), and Orientation of the parts, both to the whole and to each other !

It will also save you Time. Money and Frustration as it helps guide you enroute to the final build of your own Rocket Mass Heater RMH!

If there is a Rocket in your future Your fellowMembers here at Permies will help you find it ! For the good of the Craft ! Pyro-magically Big AL !
Let's get him boys! We'll make him read this tiny ad!
Rocket Mass Heater Manual - now free for a while
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