Mike Dinsmoor

Peter B. Onde wrote:An outdoor wood furnace is an option. It's expensive though. And while living in a place where weather doesn't cooperate in regards to keeping wood dry during transport. Hence it's necessary to have a large firewood storage in the same building as the heater. (That way the heater also helps drying the firewood.)

What I really want is a DIY outdoor furnace, clean burning with firewood storage.

Heating the greenhouse, I'm sure the RMH will do fine. It's even possible to build the heater house next to the greenhouse so that the barrel gets inside the greenhouse. The challenge will be to get most of the heat into the mass under the house - that's where most of the energy is needed.

I'm thinking of various ways to achieve that - getting more energy into the circulating water than into the room where the heater is. One way would be to cover the barrel within a coil og waterpipes. (Putting the pipes inside the barrel I think will be too hot for the piping.) Then I could put isolation outside the coil. But then the barrel probably will be overheated. One way to deal with that problem could be to NOT use a metal barrel, but rather build a "barrel" of firebricks. Then make a coil of piping around and over this "brickbarrel", and lots of isolation outside this. This may introduce another issue - In a regular RMH he barrel has a cooling effect on the exhaust. This effect may be crucial to the airflow through the burn chamber. How can that be solved? Maybe by using a metal barrel without top at the bottom and extend with a "brickbarrel" on top of that?

Does anyone have experience with isolating the barrel of a RMH? Or stacking two barrels on top of each other? How did this affect the heater?

Are you willing to go outside and feed the fire every 15 minutes? If not then forget a RMH. Even a batch is going to get old going out and tending the fire every hour or so. Thats why large wood capacity boilers are so popular for outside heaters. If your heating a greenhouse and a home in an area with cold winters, you would need to do lots of burns with a batch or RMH.

Heating water with a RMH or Batch is not very effective since you are also heating a mass and need a good draft to run the stove. If you set it up to heat any decent amount of water, your draft is dead. Your only option to do both heat mass and water is to run a blower on the exhaust. You would not need a chimney and could use PVC exhaust.

Heating the soil in your greenhouse could be done with your warm water circulated through some pipe barried close to the surface. Can you put a heater in your greenhouse?

Check this out;
http://donkey32.proboards.com/thread/3552/el-tornado-experimental-build-thread

Peter B. Onde wrote:I'd like to have a batchbox RMH. But I'm afraid that something will fail someday. So is the insurance company - if the house burns down as a result of not using a certified fireplace, they will not cover.

Ironically a properly made batch box is probably safer then a standard wood stove. There is no creosote to cause a chimney fire and the outer surface of the heater is typically cooler.

Travis Johnson wrote:

I think the absolute best sustainable way to power a radiant floor heating system is compost heat..

I was just reading through a study on this and was surprised to learn that you would get almost the same about of btu's from wood that is composted as you would burning it. The trick is to keep all the heat created from your compost insulated so it doesn't escape to the outside air.

If I had the space, I would build a large enough shed that was insulated all around, fill it with the biomass needed for a whole winter then add a heat exchanger inside up towards the top where all the heat would be. Circulate the water to the house from there.

It has been done and it apparently works well.

LuAnne Welch wrote:

I stayed with the six inch system, (thinking now I should migrate to 8").  The foundation consists of 1 inch of marble, 1 inch of dura-board rated at 2300 degrees and then a layer of 2.5 firebrick.

During the first trial I noticed the dura-board didn't stand up to the fire inside like I thought it would and scraping out the ash damaged it. So I went with #2 firebrick to line the firebox.  As you can see from the pictures, the main changes I made are I made the riser 48 inches instead of the 32 I had before.  I thought this would help with the draft.  On the manifold I started with an 8 inch outlet for two feet then reduced the ducting to 6 inches the rest of the way.   I modified the ducting so that I only have three bends instead of the previous 5 and increased the chimney to 23 feet (its all I can support).  

I fired it up, and draft is no longer an issue. The problem now is I'm not getting any heat from the barrel.  The temp in the firebox will reach up to 1850, but thus far the best I can get at the top of the barrel is 450 - 500.  Now I'm really confused.  The temp above the Tee in the chimney never got above 100, and the burn is so complete that after a day of burning wood, all that remained was less then 3/4 cup of ash.  There is no smoke appearing at the top of the chimney when it got to 500.  So the question to be asked is where does all the heat go from the firebox to the top of the barrel.   Surely and extra foot of riser would not dissipate the heat that fast.  

You went from the highly insulated board to firebrick. Maybe all your missing heat may now be going through your firebrick to the heater. You would get it back via slow release.

Yes, forced induction works very well.

Check out this thread over at donkey32 on pro boards; He runs a better blower on page 2

http://donkey32.proboards.com/thread/3473/mini-rocket-forced-induction

Hey Thomas,

Is an hour warm up normal till steam starts to appear? I would think with a ceramic fiber core it would only take a few minutes.

All that work in the video making a mold and he pours in bagged concrete.

What you want to do is GFRC. It will be stronger, lighter, denser and no holes to fill in. Spray on the face coat then hand pack in the backer.

GFRC does not use the coarse aggregate you find in common concrete. It is a 50/50 mix of cement/sand with other ingredients...alkoli resist fiber, pozolin, polymer, plasticizer, etc....

I have been thinking about ways to move heat around to other parts of the house. I use to not like the idea of using water and thought about running air ducts to the far areas from the heater. From all the research I have done, I now believe water is one of the best options. If I was doing a new construction, I would insulated the bottom and sides of the cement pad and bury PEX inside it. Water is such a good carrier of heat and takes a very small amount of energy to move around. It uses less energy then moving air around.

The other factor to consider is Hydronic heating is code and proven if that matters to your area.

One concern with running a heater under a floor would be long term viability on the cement from the heat separating out the chemically bonded water. Also, there would be the clean out maintenance. It all just seems overly complicated for something that could be done with just moving some water around in some tubing.

Still, it is a very interesting idea. I can see the benefit for a primitive era.

Do you have any clay in your subsoil? You would be surprised at how well local clay works as a fireclay substitute. My subsoil in my own backyard has amazing clay that would definitely pass as fire clay. It has lots of alumina and very little iron. I have made allot clay using the water extraction method from the sub soil in my own back yard. You can also check out construction sites and riverbanks, etc.....

If you want to learn about building a clean wood burner, read up on thermal oxidizers. Also, the 3 T's of combustion efficiency - Time, Temperature and Turbulence. Metal wood stoves are at the lower end of the spectrum on temperature and time so they are not the best option.

The US EPA regulated wood stove emissions. They do not regulated masonry heaters because they burn so clean.