Alan Bowen wrote:I need to build a shed out back and I want to put a rocket mass heater in it.I am thinking about an enclosed porch where the feed part is and the fire will
be like under the wall into the building. The enclosed porch will be on the South side of the building and it will be a dry place to store bundles of firewood.
This is important, Greenhouses are by definition areas of high humidity, we always want our wood as dry as possible and this is one way to make that happen>
That way the air that is feeding the fire will not be coming from inside the building.
But, remember the heat that flows Through the horizontal chimney is captured in the Heavy Dense Core of the Thermal Mass , It is Not vented out the final vertical chimney,
therefor it is not lost!
Just a short distance inside the wall will be the fire loop (?)
Perhaps you are taking about the Heat Riser and the TWO gas streams 1) the very hot rapidly rising gases within the Heat Riser and 2)the much cooler gases that are in
contact with the surfaces of the barrel, and are now thickening, heavy, dense, and falling vertically down the exterior of the Heat Riser ! There is No Loop!
(Then the exhaust into the bench that will be on the West side then on the North wall before exiting out through the East wall.)
Sorry, I got lost about the time I left the RMHs base -and before I got to the Horizontal pipe thru the Thermal mass! This area the Transitional Area is critical to get right !
This would just be a testing mass heater. The idea is to head back there on a cold winter day and see what the mass heater will do. If I keep a fire going for 24 hours or
until it is warm in there then just let the fire die down to see how long the warmth lasts. Ultimately what I want is to build a greenhouse with one in it.If I could just feed
it several times a day and the mass would carry it through the night I would be so happy.
A couple of hours a day maximum tending to the RMHs needs by ear with no more thought than you would use in adjusting your glasses = 20 - 30 hours of heat !
this is much later, even days later after the core, the insulation, and the cob have all dried out !
Also I must ask if anyone thinks water can be the mass.
For your first RMH inside a Greenhouse - 55 gallon drums at ambient temperatures during the day will rarely fall 10 degrees over night, elaborate plumbing is rarely
needed if you are just trying to add a month of greenhouse use at both ends of your Growing season !
Originally I was planning to use an old cast iron wood stove I have that has a water jacket around it and two threaded holes to plumb it up with 3/4" pipe. I was going
to place 12 plastic 55 gallon drums around the greenhouse with the grow beds on top of them. Insulation wrapped around all of the barrels would make almost all of
the heat go up through the grow beds. I was going to push water through the stove then through all of the barrels. The cast iron stove would have been radiating heat
into the whole greenhouse.
I know the rocket stove will burn a lot cleaner and get more heat out of the wood. If I can wrap enough copper line around it do any of you think the water barrels
would be okay to use?
This is a poor place to try and extract heat, the water jacket will tend to hold temperatures at the boiling point of water which is well below the temperature
required to burn creosote, and still capable of turning water into steam !!
After the barrel - within the first 5' of the horizontal pipes run through the Thermal Mass is usually a safe area to run large diameter tubing as part of a
I have insulated double pane sliding glass door panels to use for the glass parts of the greenhouse. If I had row covers on the grow beds just think about all of the
heat that would be stored in those barrels radiating up through the grow beds then it is trapped under the row covers.
The lower the thermal mass is positioned the more effective the row covers will be !
My idea would be a 3/4" Galvanized pipe to the rocket heater then to a header pipe with a lot of smaller 3/8" copper lines going around and around the rocket stove
before heading them all back into a header pipe of Galvanized 3/4" then around to all of the barrels. I do have 100' of 1977 3/8 copper that has never been out of
the cardboard boxes. I also have an old pressure tank that I would use upside down as an expansion tank in the system.I probably would just drill holes in the header
pipes and tap them to fit 3/8" pipe to flare adapters.
Ask a Firefighter! When you reduce the inside diameter of the pipe by !/2c you reduce the Sq. inches to 1/4, and lose even more proportionally to friction loss, so the
actual flow is closer to 1/5th! In this case the 3/4 pipe you started with is too small for the job you are asking it to do !
Alan in Michigan
A Michigan Redneck