to those looking to regulate their hot water temp
for a domestic supply, check out 
Bay Voltex in Pleasanton CA

they make temperature controlled flow valves for a wide array of
things, inc. lasers which is how i know about them .....

you'll probably have to find a distributor for them in your area, but
companies are usually willing to tell you this. If they tell you they
dont sell direct tell them you need a distributor for 'quantity 1 to 5 
thousand' (not specifying that the 1 is one and not one thousand!!!)
and you will get 'action'.  If you're really feeling lucky you can 
ask for engineering samples hee hee (these are some of my best trade
secrets on how to build a hobby on everyone else's back ....)

sorry i took so long to remember but i am going senile - still in
shock over Nubus too.  :-(