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

[Amanda Peck]

Boiling water might well propel itself along into the hot tub, especially if 
it was a (-n unpressurised?) loop.  It might be after the tub was plenty hot 
and you tried to turn the heating OFF that you'd run into trouble.  Although 
positioning the pipe so that the intake was low enough that the water 
wouldn't go out from both ends, leaving an empty pipe in the firebox might 
be necessary.

Somebody else mentioned putting coils around/embedded into the cob of the 
oven, didn't they?

Wood-stove hot water heaters look from the pictures anyway like they're apt 
to be tanks hanging off the stove.  But I've never seen one to look at 
carefully.

I got a Kelly Kettle for Christmas.  Cute little job with the kettle part 
surrounding the chimney.  There's a small learning curve there.  I didn't 
exactly boil my water for tea in 3-5 minutes (guy in the link didn't 
either).  But while I was fussing with the thing, I was wondering if that 
would be a great idea for using up extra heat to make hot water. In lots 
bigger form, of course.

http://outdoors-magazine.com/s_article.php?id_article=126
.............
Ed wrote:
     It seems to me that the old wood stove water heaters just used 
galvanized
iron and depended on convection to prevent the pipes in contact with the
flames from exploding. Have you checked out water heaters for wood stoves?