[Cob] Horizontal flues in cob applications

[ocean]

To Dave T. and others -

I read that you are interested in heating thermal mass (cob) with a 
fireplace flue.  The problem with horizontal-running flues in regular 
fireplaces has been discussed on the list before, and I wrote the 
following reply some months ago about Ianto's rocket stove (which has 
recently been published in a detailed book at 
http://www.rocketstoves.com - I highly recommend the book!)  I don't 
know if you can use a rocket design to burn other fuels than wood, such 
as oil, etc.

Good luck!

Ocean Liff-Anderson
Proprietor, Intaba's Wood Fired Eatery
http://www.intabas.com

-------------From my prior coblist posting...------------

As far as I'm aware the ONLY way to do this right is to build a 
Ianto-style rocket stove...normal wood stoves require a tall, vertical 
chimney to draft properly. If you take a regular wood stove and try 
force the flue horizontal, the most likely occurance will be the fire 
will go out and smoke will fill your room...

Ianto refined the rocket-cob design for over a decade, and the reason 
his rocket stove works with a long (up to twenty foot!) horizontal flue 
bench is specific to his rocket design. (If you don't know what a 
rocket stove is, it's a little elaborate to describe over email, so I 
strongly recommend buying his new rocket stove book!)

The key feature of Ianto's rocket is a super-insulated internal 
chimney, which he calls the "heat riser", which allows the wood to 
completely vaporize and burn at temperatures up to 1100F, so that only 
steam and carbon dioxide exit through the flue...no ash, no creosote, 
no chimney flue fires! Actually, it's instructive and somewhat amazing 
to smell(!) the exit gasses from a blazing rocket stove flue: no smoke, 
just steam more like a laundry-dryer vent with a nice woody scent!

So a well designed rocket stove combusts as close to 100% efficiency as 
anything I've seen. Why is this important, if wood fuel is plentiful? 
For one, no smoke to pollute our air. But note also that more efficient 
burning means more heat from less wood, hence less physical labor or 
money spent acquiring fuel, more time for other activities (gardening, 
reading, dancing, weaving, etc!)

Regarding the appropriate-ness of building a rocket stove versus some 
other heat source for seldom-occupied buildings... we decided to 
provide two heat sources in the cob Kiva at Ahimsa Sanctuary ( 
http://www.peacemaking.org ). We have both a rocket (built by Kiko) for 
long term heating of weekend-long events, and a Rumsford hearth (built 
by Ianto) for providing immediate heat in the previously unheated 
building for evening-only events. The Rumsford fireplace burns hot and 
clean, and provides immediate, intense radiant heat (it melted a 
plastic bucket 5 feet away!) while the rocket heats a buried-flue bench 
as well as radiating heat through its drum.

Cobbing Always, Ocean Liff-Anderson

-----------------------------------------


On Jun 4, 2006, at 11:38 AM, Whidbey Island Soap Co. wrote:

> Thanks Bill!
>
> I don't really need a lot of heating in the Pacific Northwest here. 
> Just
> something to keep it warm on cold nights. The corn stove looks like a 
> good
> promise for the mid west with lots of corn available. Unfortunatly 
> here I
> think I would have trouble finding corn for a decent price. I can get 
> wood
> other fuels here. I was thinking something like a small fireplace and 
> then
> wrapping the the flue back and forth inside a wall then up and out. 
> This
> would give the  heat a greater chance to be absorbed by the wall and 
> then
> released back into the room. Even if I had to go to burning coal I 
> could do
> it. My home and rooms in it will be prety small so I do not need to 
> heat
> large spaces. I will also be using pasive solar to heat the house and
> probably in floor radiant heating of some type. The in floor would be 
> cool
> to do by heating the water with waste oil from deep fat friers. I can 
> turn
> that into bio-diesel prety easily since I own a soap making company 
> and the
> chemistry to make soap or Bio-diesel is prety simmilar.
>
> My idea for my home is to build two or more structures no more than 200
> square feet and connect them with breezways that can be inclosed in the
> winter. The infloor radiant heating hoses would be run underneath the
> breeazways. All floors and breezways would be earth floors since they 
> tend
> to be easier on the feet and seem to radiate the heat prety well.
>
> What do you think!
>
> Dave T
>