pressure/relief valve spewing daily

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    • #272698
      Avatar photoMasterPlumbers

        My girlfriend’s house is base board heated (forced hot water) by a gas boiler/burner which has a pressure relief valve that tends to expel a cooler full of water daily. The water is hot upon expulsion. Our concern is the dialy amount disbursed.
        Neither one of us is fimiliar with this type of heating unit. Can anyone shed some light on why water is being disbursed daily?

      • #286147
        Avatar photoScott Bryan

          Pressure relief valves are just that they open when the pressure is greater than the setting on the valve. On most hot water systems the relief valve is set to open when the pressure is greater than 30 lbs. The valves also open when the water temp is greater than the setting on the valve. Sometimes the valves are just old and need to be replaced. I would check the guage on the boiler to see exactly what the pressure is (12 lbs is avarage) and check the temp (180 deg. is avarage). If they both look good you may just have to replace the valve. Be sure to get the exact same rating on the new valve. I hope this helps.


        • #286148
          Avatar photoSylvanLMP

            According to the ASME section IV code a low presure boiler (hydronic) is up to 160 PSI or 250 Degrees but the majority of the the boilers are rated to a working pressure of 30 PSI and under 220 degrees.
            Having a boiler “relief valve” (Safety on steam) discharging daily is a sign of a problem as this is a SAFETY device not an operating controller.

            Allowing this valve to continue to operate will shorten the life of the boiler due to fresh water taking the place of the water already in the ststem and thus allowing oxygen to enter and rusting out the boiler and circulator.

            This condition could be from a defective fill valve ( factory set at 12-15 psi) OR a flooded expansion tank OR a diaphram tank that lost its charge OR a run away burner firing condition.

            Do to all the possibilities I would strongly suggest you contact a licensed Master Plumber to have him/ her check out your system. Now for your protection MAKE sure they are indeed licensed and not sending some unlicensed dabbler over.

            This is for your protection.

            Good luck SylvanLMP


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