paul has a new video  

 



visit the thread.

see the DVDs.

  • Post Reply Bookmark Topic Watch Topic
  • New Topic

stratification chamber for a rocket mass heater  RSS feed

 
master steward
Posts: 22937
Location: missoula, montana (zone 4)
bee chicken hugelkultur trees wofati woodworking
  • X Likes 7
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Shamelessly stolen from the world of masonry stoves, the word "bell" with rocket mass heaters can mean several things.  So we go with "stratification chamber" to reference heating the mass (as opposed to the similar stratification that happens in the barrel).  Matt Walker is building the outdoor rocket mass heater with smoker as he describes the stratification chamber technique he prefers.  He likes to use a half barrel.  

He mentions filling a tub with water and if you flip it upside down, you fill it with hot exhaust gasses.   It comes with interpretive dance!  I felt like it might not be clear to everybody, so I paused, added an animation and description, and then rewound and did the thing with matt again - my thinking is that on the second pass it makes a lot more sense to everybody.

My animation shows filling a bucket with water because the water is heavier than surrounding air.  Then I flip it upside down and fill the bucket with hot air.   This is the same sort of effect you get with a hot air baloon.  I then demonstrate that the bucket conducts heat, so the gasses in the bucket cools as the surrounding air is warmed. 

In time, the heat stratifies with the hottest air at the top and the coolest air is at the bottom.

A regular rocket mass heater has a duct that starts low and finishes high.   The heat is forced to the far end of the bench.  The vertical exhaust near the barrel gets a bit of extra heat to make it rise - a tertiary thermosiphon.

All the crappy animation is by me! 

On a larger scale this would be called a kang bed stove or a roman hypocaust.  

After raising the manifold exhaust, use a hollow bench - with a large cavity.   The hot exhaust enters the chamber and spreads out evenly.   Then the coolest gasses are extracted from the bottom.


More about rocket mass heaters in our DVD set at

https://richsoil.com/wood-heat.jsp




 
Mother Tree
Posts: 10256
Location: Portugal
1002
bee bike books duck forest garden greening the desert solar trees wofati
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Awesome!

Matt has a slightly longer video discussing similar material - rocket mass heater Bells and Benches Discussion

 
pollinator
Posts: 1455
Location: Vancouver Island
29
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Yup, I've built benches that way too. Old Permies post And found it worked quite well. I'm waiting for the next big thing... getting the smoke to go down hill. (which has also been done before) Where instead of a chimney, The flue is directed through the earth (such as the under the "umbrella" of a high mass annualized solar home) till it is chilled enough it flows out at ground level downhill of the dwelling. The weight of the chilled flue gases can pull the warmer flue gases in the right direction. Siting would be important as a hollow below could collect the CO2 and be hazardous. (don't go "rollin' in the clover)

Anyway, I have not had the time or the room to go much farther with this. I had hoped we would be moving to a larger chunk of land before now so I could build a high mass house heated with a high mass heater to try this out more thoroughly. Possibly in another year.
 
Posts: 153
Location: S. Ontario, Canada
3
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
This is the same principle behind the operation of any RMH which incorporates a bell (stratification chamber) instead of having a serpentine flue running through a horizontal mass. This is the same physics as I used in designing and building my 7” steel cored air-cooled RMH inside a steel furnace oil tank which is covered in cob.  You can see this build at https://permies.com/t/69632/Building-tube-steel-air-cooled. ; Then see the convection oven I added on top of it to utilize the heated fresh air rising from the air jacket at https://permies.com/t/72646/cost-convection-oven-top-steel

My next addition (In the spring) will be a bench as described above,  the purpose of which will be to extract more heat before venting to the chimney.
(24)-Final-coat-of-clay-paint-project-completed-and-fully-operational..JPG
[Thumbnail for (24)-Final-coat-of-clay-paint-project-completed-and-fully-operational..JPG]
(26)-Old-BBQ-body-is-now-a-convection-oven-on-top-of-RMH-bell.JPG
[Thumbnail for (26)-Old-BBQ-body-is-now-a-convection-oven-on-top-of-RMH-bell.JPG]
 
Posts: 43
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I have seen barrels used over a barrel stove to steal more heat before it leaves through the flue.

I wonder, if a barrel could be adapted onto the flue exit from a standard wood stove, to act as a bell/strat chamber?
Something like Peterburg's three barrel bell, but using a standard UL approved stove vs an unapproved batch rocket heater.

a bypass could be built in for easy lighting, then close it for the heat cycle.

if a large amount of mass was added to this, a small stove burned HOT could be used to cheat the local bylaws and such.
 
Len Ovens
pollinator
Posts: 1455
Location: Vancouver Island
29
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Brad Hengen wrote:I have seen barrels used over a barrel stove to steal more heat before it leaves through the flue.



not really the same thing as the ones I have seen exit higher than entrance and of course there is no mass.


I wonder, if a barrel could be adapted onto the flue exit from a standard wood stove, to act as a bell/strat chamber?
Something like Peterburg's three barrel bell, but using a standard UL approved stove vs an unapproved batch rocket heater.



There are two difficulties here. The first is that the flue and how it is run is a part of the "UL approved" part. Certainly the permit inspector
will expect it so. Secondly, without mass, the tin stove will get run at an idle because it will be "too hot". The bell will only make this worse
if it has no mass around it... that is if it is only made out of a barrel.


a bypass could be built in for easy lighting, then close it for the heat cycle.

if a large amount of mass was added to this, a small stove burned HOT could be used to cheat the local bylaws and such.



If you used the permit process either you would install as per stove manual and modify after inspection rendering it no longer inspected or
you install lots of mass and end up with a masonry heater which has different rules and probably gets rejected and you remove it.

Better to get a professionally installed masonry heater with bells and or benches that will pass inspection. A proper steel wood stove
will cost as much as $5000 installed properly and a properly installed masonry heater can be as low as $10000 depending on the available foundation.
Oh ya, foundation. Mass requires a foundation to carry the load. This is not that expensive if it is designed into the original foundation or even fitted
later if access is easy. It could be expensive if your floor falls through. Part of the reason for getting a permit is to get a mortgage... mortgage requires
insurance. If you ever use that insurance with a modified wood burning appliance the insurance is void.

So in my opinion, you either do the whole thing non-permitted or you make sure your inspector is happy with what you are doing. If you are able to do
something in a non-permitted context, a rocket stove or masonry heater from the ground up just makes more sense. A masonry heater can be made with
the same number of fire bricks as the rocket mass heater with the rest being clay or home made adobe. So the price if permits are out of the picture is similar
for both. I would suggest the skill level is not that different either.

I have no opinion on which is better between RMH and masonry heater, but Frankenstein heater... not unless you have more skill than average and just like to tinker.
 
gardener
Posts: 2372
Location: Upstate NY, zone 5
83
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
The RMH is actually a subset of masonry heater, with specific combustion core features. It also usually is owner-built with less expensive materials, but this is not a requirement.
 
Len Ovens
pollinator
Posts: 1455
Location: Vancouver Island
29
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Glenn Herbert wrote:The RMH is actually a subset of masonry heater, with specific combustion core features. It also usually is owner-built with less expensive materials, but this is not a requirement.



Yup, I try to stay away from saying the RMH is a masonry heater because there are some people who feel they are a different beast totally. I get less flack 
 
It's just a flesh wound! Or a tiny ad:
2018 Homesteader PDC (permaculture design course) & ATC (appropriate technology course) in Montana
https://permies.com/wiki/74470/permaculture-projects/Homesteader-PDC-permaculture-design-ATC
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!