Matt : Just a little background, 1st came the Rocket Cookstove, very efficient at turning twigs and small wood into Heat Energy. Mostly because the type of insulation surrounding the
combustion chamber, This was developed for third world counties where 40% of The People still cook on 'three rock fires'! A vast improvement over the rocks but much of the Heat
Energy produced by our efficient burn still was lost to the environment.
The
Rocket Mass Heater, RMH burns super efficiently, ( zero creosote ) with 40% again being the prompt heat That Makes the push me - pull you magic! Think of that Lost Heat as the
work energy that allows use to flow the remaining hot exhaust gasses Up to 50' Horizontally while giving up its heat energy into the thermal mass, and the temperature of the gases
in our final Vertical Chimney, being around 140dF!
Air Is an almost perfect insulator, and is actually a damn poor material to store or transport Heat, but we have a legacy from the days of Cheap Fossil Fuels, and forced air heat, of
thinking this must be the way to go ! - We burn Fossil Fuels, or Wood, literally Frying our Air Trying to get it to hold enough heat to make us feel warm ! Without ductwork to channel
our hot air from room to room ( and don't forget a return air supply must be allowed for ) We are trying to herd cats and are grateful for any Air/Heat flow at all, preferring not to think
about the fact that our ceilings are the warmest part oft he house!
The 50' running feet of thermal mass can be made into a bed, or couch/ bench or built up to be a kitchen counter with cooking surface and/or ovens/warming areas. It can also be
configured (House shape making it practical ) into a continuous heat source and a piece of Fine Hand-crafted built-in furniture running from your primary room into a second or even
a third room!
The 1st 40% is radiant energy that travels though the air to a solid object ( hopefully you!) that object warms up and the we get some warming of the air, the Last Heat the 60% of the
Heat Energy Now stored in the Cob/Thermal Mass Warms its surroundings slowly and for a long time through conduction or direct contact, Your But to the Bench.
In retro fitting an existing house The RMH will always out perform a space heater type of un-ducted Wood Stove for Efficiency, smooth even heat over a longer period of time,
and in comfort when properly Built!
Generally we use ductwork within the Thermal Mass to channel our hot exhaust gases, but we do away with any need for ductwork to move air! We are trading the need to plan carefully
for the bulkiness of our built in furniture/Thermal Mass and the barrel, to totally avoid the need for air handling ductwork with its own poor efficiencies !
I hope this helps ! Read the book a couple of times, and come back here and get help on this and other projects from your nearly 25,000 Fellow Members ! Big AL !