From: peterwieck33@gmail.com   
      
   It is called a "tempering valve" - what it does is, theoretically, prevent   
   scalds by not allowing the hot water to run alone. Some are thermostatic, most   
   are pressure-based. Those that are thermostatic tend to fail-cold. Those that   
   are pressure-based can    
   fail either way, or altogether. Generally, one must replace the cartridge -   
   that is the internal part that does the mixing - to fix either. In hard-water   
   or high particulate (sediment) situations, failures are quite common and can   
   be very annoying.     
      
   Peter Wieck   
   Melrose Park, PA    
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)