Ruudglass pacemaker Model RSPER-120-1 manual. Just want to find out what is the appropriate or right relief valve to replace the one installed on mine. My heater is not getting energized electically but the water is being heated thru our solar system. But lately relief valve starting to open when the water in the tank reach 140 degrees. I had this heater for over 10 years now and only now started acting like that.