[Cob] Rocket vs. Rumford for Patio Heating

[Ocean Liff-Anderson]

Been reading this thread and want to clarify an important point:

Outdoor heating requires "radiant" heat, especially since you are  
cooled by any breeze which might blow through or around your patio.   
This is why the free standing propane heaters work so well - they  
provide 100% radiant heat.  On the other hand, "conductive" heat is  
ideal for storing heat in thermal mass which is released gradually,  
best for heating buildings or enclosed spaces.

Rocket stoves are good conductive heaters and but not very good for  
outdoor/patio heating - ideal for storing heat in thermal mass  
through the cob-encased flue bench in Ianto's design (which is absent  
in the African cook-stove Rockets previously discussed in the  
coblist).  Ianto's Rocket drum radiants heat primarily off the top,  
not as much from the sides of drum.  So in an outdoor patio, you will  
be standing around your rocket and warming your hands over the top  
all the while shivering due to your chilly lower quarters.  The  
Rocket's heated bench does help a little, but any breeze quickly  
negates the effects of a warm butt.

On the other hand, the Rumford hearth is primarily a radiant heat  
source, where heat is projected (for lack of a better word)  
horizontally out to the people sitting or standing around it, warming  
hands, legs, torsos or butts - depending on which side of you faces  
the hearth.  At Ahimsa Sanctuary, we hired Ianto to build us a  
Rumford in our cob kiva.  We had it fired up while plastering, and  
the Rumford put out so much heat that it melted a 5-gallon bucket 6  
feet away!

Here are pics of our Rumford being built and fired up.

http://www.peacemaking.org/cobpics/rumford1.jpg
http://www.peacemaking.org/cobpics/rumford2.jpg
http://www.peacemaking.org/cobpics/rumford3.jpg
http://www.peacemaking.org/cobpics/rumford4.jpg
http://www.peacemaking.org/cobpics/rumford5.jpg
http://www.peacemaking.org/cobpics/rumford6.jpg
http://www.peacemaking.org/cobpics/rumford7.jpg

Rumford hearths have very specific design requirements so that the  
flue and draft work properly.   I don't know of any published cob  
plans, but I did Google into a site out of Port Townsend, WA which  
sells a masonry (brick & mortar) version:  http://www.rumford.com    
This is pretty spendy, as most conventional masonry construction is,  
and not really what we are looking for in the cob building movement.

So if you'd like to integrate a Rumford into a cob wall or building,  
I would suggest contacting Cob Cottage Company for info.  Cob Cottage  
has built several Rumfords into courtyard walls with adjacent cob  
bench seating, the most prominent one on the cover of the Hand  
Sculpted House.

Good luck!
Ocean Liff-Anderson
Steward, Ahimsa Sanctuary
http://www.peacemaking.org
Proprietor, Intaba's Wildfire Restaurant
http://www.woodfiredeatery.com


On Oct 6, 2007, at 6:08 PM, michael montagne wrote:

> So I look at pictures and diagrams of rocket stoves and I read how  
> they work
> and where to clean what when but a question still remains.  Are  
> these 55
> gallon steel drum heat exchanger containers just upside down  
> barrels?  In
> other words, is it necessary to open the top for maintenance?  If  
> not, why
> don't more people just substitute cob for the steel barrel?  I  
> guess that's
> really more than one question.  Also, where to source the smaller  
> barrel for
> the feed tube?  I'm in Portland, Oregon.  My stove will be outside,  
> heating
> a small covered area of my deck to allow use during the cooler months.
>
> -mjm
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