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

[Amanda Peck]

Coiling iron pipe?

Remember that the big, or even medium-sized, earth ovens will first fire to 
over 500 degrees (F), you let  the fire go out--and/or rake it out, and then 
cook first pizza, then bread, and then, if you've got enough thermal mass, 
something like a slow-cooker meal overnight.  By the end of the bread you 
still should have 300 degrees in there.  The big horno in Mexico (and it WAS 
big) I've seen in action went through three or four bakings of rolls 
starting early in the morning, and there was still enough heat in there to 
safely cook a giant--pork--tamale, still quite warm the next morning.  The 
cob ones we see pictures of from list members won't keep that much heat THAT 
long, but long enough to burn the first batch of bread or rolls, then do the 
next nicely.
...............
KC Chandler respnds to Karl and me (snipped):

The fittings don't go into the stove; only the coils do. Your fittings are 
outside of your heat source.
Your problem won't be in overheating the hottub (let the fire go out) 
...it's not likely that you can heat it faster than the water in the tub can 
cool, even if a small tub, even if it's covered.
But, I'd be interested in seeing someone try.