The boiler feed valve should be factory set at 12 psi,�but there are a couple things you can check to make sure it is set properly. First, make sure the fast fill lever is in the "A" position. If the pressure is still too high, loosen the lock nut on top and turn the screw counterclockwise several turns. Then release the pressure in�your system and slowly turn the screw clockwise until your gauge reads the desired pressure. Finally, re-tighten the lock nut. For further details, see page 2 of the instruction manual.�