Nick Portinson : It amases me how many people get nervous about the thermal mass bench ! Let me try to give you a possibly better way to look at a Rocket
system.
Correctly running a rocket heater is done by ear, we want to create a freakishly hot Fire ~1100ºC~ to gasify the wood fuel, at these temperatures we get a Hot
clean burn with very little particulates fly
ash or pollutants , just very high efficiencies, with the highly Refractory materials we use to surround and insulate the
combustion core this happens within 5 minutes.
This threshold can be easily observed in a darkened room as the Burn Tunnel will glow a dull red, from that point on it is possible to throttle back the amount of
wood and its necessary combustion air, and still receive the benefits of a clean burn. This is totally unlike trying to load a lot of wood in a 'regular
wood stove'
and then closing it down to last a long time, which results in a great loss of efficiency !
Placed in a good centralized area within your workshop, you will be able to quickly hear and observe Your Rockets needs, tending it is an automatic response
that you make to your Rockets needs with no more conscious though than you take in adjusting a pair of reading glasses!
This attention given while you work in Your garage, over a period of 3 - 6 hours will when coupled with a Thermal Mass Bench to store and re-radiate the heat
energy will give you 12- 24 hours of additional heating!
Think of the Thermal mass bench as a custom made work bench that can be just as high or low as you want it to be! A custom job built just to make your work
stations more productive, or the Thermal mass can be routed underneath existing benches, I can not speak for your work shop but my
experience is that the
space under most work benches quickly fill up with stuff and never gets the cabinets you promised yourself that you would build there !
So- The Rocket Heater is Very, Very efficient at turning the Chemical Energy of your wood fuel into Heat energy, ~40%~ of the heat energy thus made is radiated
off of the surface of the barrel, it is at this point that your next decision ether condemns your Rocket to being a poor
wood stove or a super efficient heater that
allows you to use 1/5th of the wood of a regular
wood stove!
Are you going to vent the hot exhaust gases outdoors like a conventional
wood stove, or are you going to make the next step a positive one, build a Thermal mass
bench, and capture the additional 60% of your Rocket Heaters Thermal energy !
Will you come in from a day in the fields to a cold Garage structure, or to a warm workshop !
So we have addressed size, for a 1st time build a 6'' system is very doable, and can be fed much less wood which burns freaky hot and efficiently, as compared
to a smaller unit that No-one here at Permies.com is going to recommend for a 1st time build !
We have discussed the idea that Your Rocket will constantly tell you how 'happy' it is, tending it is not unlike having a plump bank account into which you make
regular small deposits, and get Automatic withdrawals in the form of heat, pleasant, ever present, bone warming heat !
Bench location can ether be finessed to give you a new workroom, or be the single stumbling block that keeps you from heating your garage with no more than
the scraps of wood that pileup in every odd corner and hedgerow on your farm !
Our Fellow members are correct about the fate of Iron and Steel in the Rockets core, A google search can connect you to articles on 'High Temperature Hydrogen
Attack' and 'Hydrogen and Steam Embrittlement' !
As they say- "Rome was not built in a day'', if you continue to come back here to
Permies.com eventually we will infect you with the Delightful madness that is
Rocketeering ! For the Good of the Craft ! Big AL
