new videos
hot off the press!  
    more about rocket
mass heaters here.

more videos from
the PDC here.
  • Post Reply Bookmark Topic Watch Topic
  • New Topic

Rocket stove UNDER - inground - buried home.  RSS feed

 
Dave Lot
Posts: 128
5
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Started a thread over in the home section, but since this is a problem for the rocket guys, I will start a thread here . .

So, here is the idea . .

8 inch system. - start of the system (fire pit) on one side of the house - inside the house. Chimney run is a straight run all the way across the house, under the slab - with no bends (for easy cleaning) - exits outside the house beside the slab - fully poured concrete pier up against the wall encases the vertical chimney - insulated right up level with the roof - from there you have a standard chimney going up as high as needed. - only 1 90 degree bend in the chimney with this idea. with no roof or wall penetrations too leak and cause problems.

Now, before you start screaming , the problem with this idea, is where too locate the clean-outs. I was thinking about running the chimney up along the far wall - indoors, but then I would have too exit through the roof -(not going to do with an underground roof) or put another bend in it too go through the wall - then another 90 to go up - more than code allows . . problem there.

So if I run the chimney outside the house, I can put a 45 degree elbow right near the stove as a clean out, then have another one at the base of the wall for another cleanout . . see the picture... run the brush from the stove too the wall then vaccum - run the brush down from the top - then vaccum - all done.

I am just tossing out idea's for this one . . . trying to make it fit. . . any suggestions would be welcome.

chimney-idea.jpg
[Thumbnail for chimney-idea.jpg]
 
R Scott
Posts: 3349
Location: Kansas Zone 6a
32
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Clean outs don't need to be 45's like sewer lines. Standard Tees would be much easier to hide the port in the floor.

You are going to have problems not having the final pump of the chimney passing next to the barrel. Your exhaust could get too cold to rise.
 
shilo kinarty
Posts: 98
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
you need good insulation under the horizontal part and around the vertical chimney
 
Glenn Herbert
gardener
Posts: 2180
Location: Upstate NY, zone 5
74
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
It looks like you are preparing for a chimney brush to scrape out all surfaces of the ducting. With a RMH, this will not be needed as there is no creosote to deposit. The most you will have is a small amount of flyash settling in the duct, and a vacuum hose run down the length will take care of it. You want to make a large manifold to transition from the barrel to duct, and include an ashpit in that with easy access. Most of the ash will settle there. Experience will show you how often various parts need to be cleaned.

What is the total length of your underfloor run? That may be an issue depending on the size of the house. 8" is said to be good for up to 50' of horizontal (minus 5' for each elbow, which you don't have any of.)

The chimney will work better rising inside and elbowing out the wall top, assuming you have a colder climate, regardless of code requirements for woodstoves. Remember that this is not a woodstove, it is more like a masonry heater. Also, you could reasonably describe the elbow rising out of the slab as the exit from the heater; then you have a situation identical to many woodstoves of one 90 going out the wall and one to go up the chimney.
 
Dave Lot
Posts: 128
5
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
R Scott wrote:Clean outs don't need to be 45's like sewer lines. Standard Tees would be much easier to hide the port in the floor.

You are going to have problems not having the final pump of the chimney passing next to the barrel. Your exhaust could get too cold to rise.


That is something to think about, since the chimney will be no where near the barrel, it could cool off . . but then I am wondering, since I am going to have everything surround with about 8 or 10 inches of Styrofoam, walls - chimney block - floors - rocket stove block - everything will be insulated. Keeping that in mind, with the opening in the burn chamber blocked, wouldn't the heat from the house keep the chimney warm year round ? Once you remove the fire chamber cover and start a fire, it should have some draw there - right ?

shilo kinarty wrote:you need good insulation under the horizontal part and around the vertical chimney


Yup, I have already contacted the manufacturer who made the 4' x4' x16' blocks of Styrofoam - that they built a highway on top of - they can custom cut the 4 x 4 blocks too any size. I am leaning towards an 8 or 10 inch slice - 16' long. All the way around. 8 inch slice would go into the 48 inch evenly. A 10 inch slice would give me more insulation value, and the extra 8 inch piece could double up and go on the roof . . .

Glenn Herbert wrote:It looks like you are preparing for a chimney brush to scrape out all surfaces of the ducting. . . . Experience will show you how often various parts need to be cleaned..


I agree, the problem is, that I will get the "experience - after the house is built . . If I do have to use a chimney brush on the whole chimney, I would rather have the clean-outs there than not. . .

Glenn Herbert wrote:

What is the total length of your underfloor run? That may be an issue depending on the size of the house. 8" is said to be good for up to 50' of horizontal (minus 5' for each elbow, which you don't have any of.)



Looks like the entire floor plan will be something around 35 x 25 feet - the rocket stove could possibly be installed on the long side - so - 30 feet under slab, then maybe 10 - 12 feet vertical - planned so far.

Glenn Herbert wrote:
The chimney will work better rising inside and elbowing out the wall top, assuming you have a colder climate, regardless of code requirements for woodstoves. Remember that this is not a woodstove, it is more like a masonry heater. Also, you could reasonably describe the elbow rising out of the slab as the exit from the heater; then you have a situation identical to many woodstoves of one 90 going out the wall and one to go up the chimney.


I will have too check the codes that my building inspector gave me, for that one , since you cannot bend more than so many degree's , - it's not a bad idea though . . I kinda like the idea of going outside - in a insulated concrete block - and not loose space inside the home . . with the chimney inside, I would loose square footage - floor too ceiling.

Good feedback, thank you ! Keep them idea's coming. .

The only bad thing about this, is I have had my rocket stove in the shed smoke back really badly, and would not want that too happen inside my home. .. but then . . . the only time my rocket back drafts, is when it is REALLY cold, and I put in too much wood. The new house would never get that cold . . so it should not happen . .

 
shilo kinarty
Posts: 98
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I kinda like the idea of going outside - in a insulated concrete block - and not loose space inside the home . . with the chimney inside, I would loose square footage - floor too ceiling.

it's a mistake.
 
Glenn Herbert
gardener
Posts: 2180
Location: Upstate NY, zone 5
74
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Actually, with the extreme insulation of 8" of styrofoam around the outside, if the chimney block is integral with the house wall, it might as well be inside - it will be much closer in temp to the inside than outside regardless of fire.
 
Glenn Herbert
gardener
Posts: 2180
Location: Upstate NY, zone 5
74
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
One thing I would be concerned about regarding styrofoam insulation is that parts of the concrete between the duct and the styrofoam will have nowhere to dissipate heat. The heat in that zone will eventually build up to close to the gas temperature in the duct, which near the fire will be several hundred degrees. I fear that the styrofoam in those concealed spaces will melt (very likely) and maybe even ignite if air can get to it (unlikely).

The only safe solution to heat buildup is to allow airflow to carry away excess heat. This would let the heat from that section become useful instead of simply conducting slowly into the ground.
 
Dave Lot
Posts: 128
5
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Glenn Herbert wrote:Actually, with the extreme insulation of 8" of styrofoam around the outside, if the chimney block is integral with the house wall, it might as well be inside - it will be much closer in temp to the inside than outside regardless of fire.


Have the chimney inside, but pour a concrete block around it ? Not a bad idea, insurance can't say it's a fire hazard (encased in concrete) I would still loose some space, but it would keep things warm . .
 
Dave Lot
Posts: 128
5
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Dave Lot wrote:
Glenn Herbert wrote:Actually, with the extreme insulation of 8" of styrofoam around the outside, if the chimney block is integral with the house wall, it might as well be inside - it will be much closer in temp to the inside than outside regardless of fire.


Have the chimney inside, but pour a concrete block around it ? Not a bad idea, insurance can't say it's a fire hazard (encased in concrete) I would still loose some space, but it would keep things warm . .


 
Dave Lot
Posts: 128
5
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Glenn Herbert wrote:One thing I would be concerned about regarding styrofoam insulation is that parts of the concrete between the duct and the styrofoam will have nowhere to dissipate heat. The heat in that zone will eventually build up to close to the gas temperature in the duct, which near the fire will be several hundred degrees. I fear that the styrofoam in those concealed spaces will melt (very likely) and maybe even ignite if air can get to it (unlikely).

The only safe solution to heat buildup is to allow airflow to carry away excess heat. This would let the heat from that section become useful instead of simply conducting slowly into the ground.


I am agreeing with ya there . . I would have too build this thing on top of a perelite and clay base - so the heat will be focused upwards into the concrete floor - warming the radiant floor tubes . . but then if I don't put in enough insulation in the mix, I may have a cold chimney pipe under the slab . . - which may transfer the cold too the house floor . . . hmmmm . . how well would the perelite clay insulate compared too eps foam ? - around the fire chamber and fire box, definately have too build in a thick layer of perelit and clay - just like in my shop stove - but under the slab - follow that ?

foam under the perelite layer ?
 
Glenn Herbert
gardener
Posts: 2180
Location: Upstate NY, zone 5
74
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Perlite-clay can be mixed very sparse on the clay and be very insulative, especialy in a contained space such as under a slab where it doesn't have much difficulty maintaining its shape. My guess would be that a simple layer of 8-10" of perlite-clay under the duct and to its sides would be close to the styrofoam insulation value and be totally heatproof.

I have mixed perlite-clay by the method of misting perlite with water, dusting fireclay on and mixing, repeating until all the perlite has a thin coating of clay. That made a heat riser fill that was strong enough after firing to resist handling and moving in a car several times.
 
Dave Lot
Posts: 128
5
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Glenn Herbert wrote:Perlite-clay can be mixed very sparse on the clay and be very insulative, especialy in a contained space such as under a slab where it doesn't have much difficulty maintaining its shape. My guess would be that a simple layer of 8-10" of perlite-clay under the duct and to its sides would be close to the styrofoam insulation value and be totally heatproof.

I have mixed perlite-clay by the method of misting perlite with water, dusting fireclay on and mixing, repeating until all the perlite has a thin coating of clay. That made a heat riser fill that was strong enough after firing to resist handling and moving in a car several times.


Thank you for the info.

In another post, I have posted the info. on the actual house progress, but here, I will focus on the heating system.

So . . an 8 inch rocket stove with the bottom of the barrel and top of the burn chamber set level with the concrete floor, before anything else is done, dig a trench about 14 inches deep and 20 inches wide . . . layer in the bottom and sides a layer of heavy on the perelite mix, - say about 6 inches deep the full length of the chimney and 6 inches on each side . . so that most - if not all - of the heat will go upwards . . so the chimney will be encased in perelite insulation - EXCEPT - for the top portion . . build it in such a way, that the top of the heat duct will be just level with the bottom of the foam under the concrete slab so when the concrete is poured the heat will be conducted upwards into the floor slab, which will be temperature moderated by the radiant tube circulating water thru the floor- spreading the heat thruout the entire floor . . see picture.

Two questions .. .
1. as I get older, I may not want the burn chamber in the floor . . what about having the chimney pipe drop down into the floor - so, from the bottom of the barrel - drop down 3 feet into the floor . . would that work ?
2. how too pour the floor and plug at the same time - with no forms ? Or should I raise the perelite box level with the top of the foam - closer too the floor and the tubing ?

In the book I have here - they have built a masonry heater and it looks like it takes up a huge amount of room . . so I would like to build my masonry heater UNDER the floor / rocket.
Still working on this one . . . .
under-slab-rocket.png
[Thumbnail for under-slab-rocket.png]
 
I was born with webbed fish toes. This tiny ad is my only friend:
Learn, Design, Teach, & Inspire with Permaculture games.
FoodForestCardGame.com
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!