[Cob] cob/earth oven also heating hot tub intake?

[tabitha and karl o'melay]

amanda, what kind of pump are you looking for?

www.stove.ru has some interesting solutions regarding hydronic coils in 
masonry heaters similar enough to cob to nick his ideas i think?

k-)

On Dec 30, 2004, at 1:41 PM, Amanda Peck wrote:

More short on space than lazy?

There are some problems I can see:

a) How is the hot water going to get into the tub?  Easiest in some 
ways would be thermosyphon but that means that the tub is going to have 
to be higher than the oven.  That way it would circulate on its own.  
Might have some temperature regulation problems there as well.

Water pressure is easy, but maybe not that easy to regulate the heat in 
the tub.

A separate hot water pump might well be the best option.  Let me know 
if you find one (I'm looking, but not very hard so far, for 
one--non-electric--to run hot water into a large container--20-30 
gallons or so--in the attic so hot showers and baths are available 
without whole system water pressure--and without toting  emptying 
5-gallon buckets of water!).  It could recirculate and be turned off as 
necessary.

b) copper pipes, sweated or soldered.  Need lead-free solder if you 
solder, need to have the melting temperature of everything WELL ABOVE 
the possible maximum temperature of the fire (not just the whole 
oven?).  There might also be some problems with expansion and 
contraction of your tubing.

c) are you going to want to be able to hot tub without baking, or vice 
versa?  I think that recycling heat sounds like a good idea.  And hot 
tubs are a great idea.  Although so far I've been thinking about Becky 
Bee's cob version for myself.

I could see some sort of moderately complicated damper system to run 
the smoke from the oven's chimney under the hot tub, or not, with 
another option to just build a fire under the tub?  A two-story 
structure--oven at the bottom with tub on top--or just off to the back 
on the bank or rock ledge up there.  If there's no handy bank or rock 
ledge, there's going to be a lot of heavy building--no little thatch 
roof over the oven, especially if one wanted the option to build a fire 
under the tub.
..........
Tys wrote (snipped)

I would like to build a cob baking oven and run copper piping through 
it,
probably in the middle of the 'fire box' area (so it'd look like a rack 
in
the middle of the oven) and this copper pipe would have water flowing
through it that would be attached to the intake/outtake of a hot tub. 
I'm
sure most of you know about wood fired hot tubs with the stove as a 
separate
unit (not a submersible).   The questions arise:

1. Could the cob oven handle the temperature differences possibly 
created by
the water flowing through it?

2. Would having a 'rack' of tubes (I imagine a zig zag pattern) going
through the middle of the oven mess up the fire? The baking?

3. Am I just being too darn lazy?



Cheers,

Tys



--------------------------------------------
Tys Sniffen
415.606.7746
Efficiency Consultant:  <http://www.ideamountain.com/> 
www.ideamountain.com




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