Rod Speed wrote:
Robert Gammon wrote

Rod Speed wrote

Robert Gammon wrote

wrote:



A 200' version makes 82%...



But that's pretty big. How about this?



We collect all the shower water in a tank, with an infinite cold
water tank next to it, then circulate the cold water through a coil
in the shower tank until it all cools to the cold water temp...
Then again, infinite tanks are hard to come by.



So maybe mix hot and cold fresh water to 90 F and circulate that
through the coil until the shower tank drops from 100 to 95, then
pump some of the 95 F fresh water back into the hot water tank and
add enough
cold fresh water to make the fresh mix 85, then circulate for a
while, then pump some 90 F fresh water back into the hot water tank
and add enough cold water to make the fresh mix 80, and so on. How
can we do this automatically, on a continuous basis? We need a 20
gallon expansion tank too. Lots of pumping, but little energy, if the
hot and cold supplies stay pressurized.



At some point the water needs to be heated to about 140F to kill
bacteria before use in showers and baths.



No it doesnt.



Do a little research and you will find that Canada HAS such a spec.


More fool canada. You cant ignore chlorination.


Not Canada, Australia has the spec

http://www.dux.com.au/tech_domestictemp.htm

Read this page, it describes EXACTLY what happened to me at 4 years of
age, why hot water heaters have this spec and why tempering valves can
be a valuable addition to homes with either very your children or the
elderly.