Surface area in the mass

Can some one explain to me the difference between these two types of flew pipes in the mass I have seen on you tube and a few pictures on here I could find. I saw a gentleman that builds a masonry stove with a mass bench that is hollow of brick and granite slabs on top that are sand and clay to seal. I also see some videos of people building a hollow cavity with 55 gallon drums that have been split in half.
I see in one of the video's the explanation of stratospheric effect in the hollow bench design and that it appears you can install the flew pipe any where in the system and its depth is the important specification inside the hollow space.

These hollow benches seem to me (not a engineer) that a 55 gallon drum split in half used as tunnel instead of actual flew pipe would have a superior ability to create surface area to move the heat into the mass with the available heat rising inside.

I wondering this because i am trying to find a way to get the appropriate length of pipe in my limit space. I have an existing gas stove i would like to replace. I like the idea i only need to plunge down from my vertical chimney into the top of the drum where its convenient.

I'm not planning a couch design i just want the function of heating so its shape or size is not a factor for myself. I was actually thinking of the mass being a bench to store the wood itself in the house and heat to dry it?

Thanks Jeff Wa.

Jeff, what you are looking for, is a bell.

http://batchrocket.eu/en/building#belltheory

Half barrel bell has been used by Matt Walker.

http://s65.photobucket.com/user/mremine/library/NYC%20Rocket%20Stove%20Build/

About bells.


http://kuznetsovstove.com/en/about-the-new-system

and again.  

http://www.stove.ru/index.php?lng=1&rs=16

Satamax Antone

Thank you for the links.
Can you tell me why I dont see more RMH's having these barrels (bells) installed instead of the flew pipe in the Masses.
I had not yet seen the whole barrel used as you showed in that photo bucket picture set. I was thinking they would be cut in half and a flat sheet of metal welded to them to get there profile down. But now i see having even a tall mass to make up for the air volume in the barrels should be acceptable. Plus a lot less work to construct as complete barrel.

I think my searches were coming up short as i thought the term bell was for the barrel over the riser only. Now i realize its a term for a displacement vessel such as diving bell or anything that would displace to dissimilar volumes(pressures). In this case hot and cool air or high and low pressure is probably closer to the correct idea or term.
This little bit of info helps a lot in understanding the system. Just when i though i had it figured out you opened up a new door. its much appreciated.

I'm interested in info on the efficiency between the two types. Not seeing a lot of bells to this point I have assumed the pipe method must have some sort of advantage over the barrel design.

This forum is amazing in its depth as I learn to find my way through FYI.

Matthew Walker's photo set is half barrels, just tucked in the mud bellow. You leave a one inch lip when you don't want a separation between half barrels.

Why don't people use it more?

Two things, they don't understand it.

And it's not as simple to build as mud around pipes in a bench. Well, so they think.

I like my cheapo method, i buy home heating fuel tanks, or tractor fuel tanks; You know, rectangular metal vessels. Cut two openings at the bottom. For the pipes to link in and out. And cover that with whatever i can get my hands on.

http://donkey32.proboards.com/thread/1817/starting-build-220mm-rocket-double

Matt Walker has just released a video that explains some of this stuff.

That answers my questions on ease of build and efficiency. Still makes me wonder why any one is using the flew pipe but it must be to keep the height down to make a couch or bench.

Thanks for showing me that video.

Is there a calculation for how much mass for a homes Square footage. To climate area like your growing area weather map.

I'm kinda leaning toward building the flues in my bench with brick.. keeping the the overall size a little smaller while still retaing mass.


Edit: scrap  that! just seen the video with Matt Walker talking about bell benches.. :) me likey very muchly!