Low Pressure Diaphragm Pressure Relief Valve

Hi While you are talking about a 15 lb valve, that is not a pressure but a weight, you can put anything on the opening with that weight, as long it is centered. If otherwise please elaborate. D

Its a pressure valve and releases pressure above 15lb/per sq inch. Water comes into the system from a water tank which located some approx 20ft above the top of the hot water tank. Water to this tank is pumped via a piston pump from another tank which is 75 ft below the level of he hot water tank and bypasses the HWT to the top tank. Water is then reticulated back down the hill to the HWT. Yes its complicated and unnecessary but its worked for 25-30 years like that. Thanks for your interest and any ideas

What size is the connection? Is the valve releasing to the atmosphere or to a drain pipe and what is the size in this case? Do you need it to make electrical contacts too? Is the valve releasing water or the damp or air. Do you want it to be adjustable or just 15lbs/in2. Material: bronze? What is the temperature it deals with? Thanks

Half quarter inch both inlet and out. Draining into a drain pipe to the exterior of the house through a half inch copper pipe. No electrical contacts. The valve is releaseing about 1 gallon a day at present, up from half a gal four weeks ago. No adjust ment required. The material is case steel body and it has rubber like insert. The water temperature is below boiling - about 80 degrees i think. Thanks for your interest

The cheapest you can go with is a pressure regulator for air. You can adjust the spring and monitor the release pressure with a manometer or adjust it once and cap off the manometer outlet. Take one that has a bronze or stainless steel valve in it and a rubber membrane. These things are very common and have about in it what you need. And almost everywhere to find. I will check for some specific release valves too.

copy and paste if in the USA:

http://straval.com/catlist-relief-valves/relief-valve-low-pressure-diaphragm-control-inline-threaded-rvi-20?size_id=292#size_table

You probably can also repair yours with some rubber sheet?