Fw: [Cob] cob/earth oven also heating hot tub intake? Boiler parts

[Amanda Peck]

Thanks Bill.  I love your posts.  You're right here--I might steal the boy 
scout hot water heater idea (does the one-way valve prevent water from going 
back into the bottom of the bucket?), BUT....

The problem with making an earth oven also heat a hot tub, though, is that 
an earth oven gets a whole lot hotter for a whole lot longer than what we 
want for our hot tub.  (finally cooling to 150 degrees [F] after 18 hours or 
so for a BIG oven).  How (and especially where) do we keep the water 
circulating throughout this period?  Letting the in-oven pipe dry out sounds 
like a bad idea, closing it off so it behaves like a small pressure cooker, 
ditto.  A whole other hot-water tank is possible, big enough that it won't 
get to boiling.  Just like the PV people sometimes heat water with their 
excess electricity.  But this was supposed to be simple and practical, not 
with a maze of valves and tanks that will hold near boiling water and so on.

................
Bill wrote:

 > Hi All,,, From metallurgy 101 ,, we find that most metals that get more
 >
 > than 400EF for a few hours will start to loose their temper/ hardness.
 >
 > That is why there was so much resistance to Non- cast Iron engine blocks.
 >
 > Ever wonder why CAST IRON Skillets are Cast Iron???
 >
 > Because cast iron can take a lot of heat, for a long time without losing
 >
 > temper/ hardness.....
 >
 > Now, back to 7th Grade Science,, at Sea level, an open pan of water can
 >
 > not get hotter than 212EF...
 >
 > Ever see a plumber solder on a pipe that still has water in it????
 >
 > That is a trick that VERY FEW, have been able to do...
 >
 > In fact I would pay to take lessons...
 >
 > So,, if enough water is flowing fast enough though a pipe, the pipe
 >
 > will not get to 212EF ,, and that is not even close to 400EF...
 >
 > Also, when I was a Boys Camp, many, many long years ago.
 >
 > We made a campfire water heater, form 8 foot of 3/4 inch copper
 >
 > pipe, a one way valve, and a 5 gallon bucket. The pipe was bent
 >
 > into a loop, and connected to the bottom of the bucket with the
 >
 > one way valve. The other end went back into the top of the bucket.
 >
 > We filled the bucket, and laid the loop in the
 >
 > campfire. The water Chugged, and spirted,, and before too long,
 >
 > we had 5 gallons of boiling water....
 >
 > We used it for the week to wash the dishes,,, don't know what ever
 >
 > happened to it after that...