I need to replace a faulty steam relief valve on my solar hot water collector. It is a threaded valve best I can tell (TACO 400-2 145 psi 240 F). I cant seem to find where to get one that is a replacement for this. Since it threads into the copper piping on the outside of my collector I really dont want to mess with having to modify the pipes to fit a differnt kind of valve. Any idea where I can locate a compatable replacement?