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Relief valve help

I have a boiler that is capable of operating >15 psi. The customer no longer needs it to run at that capacity and it hasn't for many years. Recently the inspector has requested to install a relief valve that is set to 15psi. The current relief is rated for 30psi with a capacity of 2900 lbs/hr. I cannot find a 15 psi relief with that kind of capacity, that will also fit into a 1-1/2" port. Increasing the pipe to 2" would create a pressure drop, and I am assuming we don't want that.

what are my options here? Thanks in advance for any help.


  • GGross
    GGross Member Posts: 1,070
    edited September 2023
    What kind of boiler is this?

  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,106
    Too vague.  Pictures will help... of boiler, piping & relief valve in question.  Mad Dog 🐕 
  • retiredguy
    retiredguy Member Posts: 915
    Is this a steam or hot water boiler? The correct terminology is, relief valve for water, safety valve for steam. The pressure setting for the relief/safety is dependent on the rated maximum pressure of the boiler. The pressure setting can be lower but never higher. Please explain just what type boiler you have, and as much data as possible.
  • ScottSecor
    ScottSecor Member Posts: 863
    I'll attempt to get you started on the right track.

    Most steam boilers used for heating are rated at 15 psi, as such you would use a 15 psi relief valve designed for steam.

    Most cast iron water boilers are rated at 30 psi, as such you would use a 30 psi relief valve designed for water boiler.

    It really depends what type of boiler you have, steam or hot water?