Rocket mass heater in basement

Greetings All
I have attached a few drawings (I think) of a rocket mass heater I would like to try to install by next winter. My goal would is to use the basement wall as the heat storage. This an old house that has been added on to and the basement wall to be used is (now)in the middle of the house.
Currently we use a wood furnace as our heating with a oil furnace as back up(witch we have not used in years), would like to remove the oil furnace and install a rocket mass heater as our primary heating.
Our basement walls are stone,we have lots out here and would use that with a mortar/cob combination mix. I think I saw plans where they ran the ducts up the wall instead of on the floor.

These are my questions:
1) What would be the minimum distance from the top of the heater to floor joist? I was going to put a 1 inch layer of cement backer board above the stove to protect the wood.
2) Because we are not using it to warm our buns but to heat the wall up will running the ducts up the wall work.
3) I am hoping to use the radiant heat from the heater to warm some of the house via ducts with inline fans. I thought about making an umbrella (or something like and attach the ducts to it??
4) I believe Erica out in Oregon did some work on building permits, is there anyone else have any info?
5) I know that they burn very little wood has anyone used dried cow patties for fuel? We have lots of that just laying around.
6) Would the amount of duct work be too long (approx 90')? I was thinking on using 8" duct with a slight reduction on the last 8 or 9', will that work?
7) Have you heard of anyone else with a similar plans?

Thank you for your time and I will be ordering a few of the books that have been recommended in the near future.
Kenneth

Kenneth and Valorie Wilson
RedBird Inn Farm
Antwerp, NY 13608

kenneth wilson wrote:
6) Would the amount of duct work be too long (approx 90')? I was thinking on using 8" duct with a slight reduction on the last 8 or 9', will that work?

it's hard to say how well it would work without some more details, but 90 feet is far too long a run for any 8" system that I've ever heard of. to push that long an exhaust run, I think you would need a larger system, and Ernie and Erica mentioned that larger systems just get too hot for any materials that they have found readily available.

welcome to the forum, by the way.

Tel, thanks for the info. If I move the heater around where the total duct work is more like 50 feet would that work better? What other info do I need to provide to help others who are much wiser than I make an better decision.
Thanks again
Kenneth

We have exactly the same situation, an older home with a thick rock wall basement in the middle of the structure. We are deciding whether to run the thermal mass mostly up one wall. or to distribute it along several walls. For us, the layout of the room makes running it up a particular wall the best choice, but we will then be focusing the heat transfer into a smaller portion of the upper floors. In the long run, it makes more sense for us to do some excavation, and run the mass along 3 walls to get more even distribution. I got some 8" heavy wall pipe so that we have the option to go up the wall and not get crushed by the tons of mass piled onto the pipe if we decide to go that route. I was able to get this 3/8" wall pipe in exchange for engineering advice I have given a friend over the years, normally it would run at least $200+ bucks at scrap prices for 40ft. Keep that expense, and the need to have a lot of help to get the pipe in place if you decide to go that route. The other option would be to use brick, rock, concrete, ect. to build a stacked wall around a thinner wall ducting, but you will have to be very careful not to crush your exhaust run. You will have to engineer in structural columns with spans to carry the weight of the mass, or you will crush your pipe.

Your distance from the basement ceiling would not need to be much, as long as you have at least 6 inches of mass on top of your upper pipe run. It would be very hard to get the temps of the top of your mass above 200°, if it has been run up the wall, with at least two turns (3 runs), especially considering the amount of mass in your existing walls.

Good luck, you have the foundation for a great system.

do you have an office in the basement? TV room? workshop? some reason that you are in the basement for several hours a day?
if not dont put a heating unit in the basement! you wont use it or tend it as it needs to be used and tended.

Shane
I didn't think of the weight on the ducts but I do have several cast metal pipes I might be able to use to go around them for protection. I also was thinking about off setting the ducts a bit making the top what ever the minimum thickness and the base wider to disperse the weight better.
Thanks for the help

Ernie
The basement is not a living area but I do use it as a workplace often in the winter, Valorie is cold blooded and likes a warm house and tends the wood heater about every hour or so. Is the tending to the heater several time a day: for making sure there is amply wood for the fire? Form what I have read if it is built correctly as long as it has a supply of fuel they run well, I have not got any books all online research?
Thanks I enjoyed all your info videos, writings, etc, very eye opening.
Kenneth

its a fire so it needs tending. you will load every 1 to 2 hours usually 2 and this means two loads is 4 hours of heat; unless a person of power shows up and the actual occupants expose him for the slug

Ernie
Thanks that helps in our planning.
Kenneth

Ernie
Thanks that helps in our planning.
Kenneth