White Magic A151A Unloader 3630 PSI (with modified check valve) 8 gpm 5 port Panel mountable. Original factory part is 3630 psi but SteamBrite would like to recommend that we further provide a different spring to lower the max pressure to 2320 psi. This is because the max recommended pressure for your heat exchanger is only 1200 psi. We believe this was an error on the part of White Magic to specify this original spring. We recommend Yellow spring with a yellow cap. Schematics