[Greenbuilding] Special valve

[Justin Close]

Speireag,  
    It sounds like what you need for your valving problem is a check 
valve with a high crack pressure.  I am not sure how high of a pressure 
cut off you are talking about (50, 60, 80PSI?) but you might be able to 
find such things.  They only open up at the pressure stated and prevent 
back flow at the same time.  You might be able to stick a couple of them 
in line with each other (two 30's makes a 60?). 

Or maybe something along the lines of a pressure release valve.  That is 
what they have on top of water heaters, isn't it?  I don't know what 
kinds of flows they are rated at, though.

-- Justin