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  • B&G FB-38 boiler fill valve

    Should the valve that is piped in ahead of the valve be open or closed under normal operation?

    After reading the manual it seems that they suggest leaving that valve open for automatic refill, but in the pressure adjustment instructions, they say to close the valve once you have adjusted.

    The system in question is about 40 y/o and has an overhead steel overflow tank in the rafters. 3 zones with B&G series 100 pumps on each. Burnham boiler. I can't find the BTU or model # marked anywhere on it.

    After running the system for a couple hours, the pressure will creep up from 24 psi to 30 psi and trip the pressure relief valve. This sometimes occurs while the system is static too (none of the pumps are running).

    Thoughts or suggestions?

    This is one of only a handful of systems that I have worked on over the years left over from my grandfather's days. I do 99% plumbing now, though I'm trying to learn more about hydronics.

    thanks,

    Chris

  • #2
    Re: B&G FB-38 boiler fill valve

    NHMaster pointed me to a solution here:
    Heating Help

    Just wanted to post it in case anyone else has a similar question

    Comment


    • #3
      Re: B&G FB-38 boiler fill valve

      Originally posted by Swade Plumbing View Post
      Should the valve that is piped in ahead of the valve be open or closed under normal operation?

      After reading the manual it seems that they suggest leaving that valve open for automatic refill, but in the pressure adjustment instructions, they say to close the valve once you have adjusted.

      The system in question is about 40 y/o and has an overhead steel overflow tank in the rafters. 3 zones with B&G series 100 pumps on each. Burnham boiler. I can't find the BTU or model # marked anywhere on it.

      After running the system for a couple hours, the pressure will creep up from 24 psi to 30 psi and trip the pressure relief valve. This sometimes occurs while the system is static too (none of the pumps are running).

      Thoughts or suggestions?

      This is one of only a handful of systems that I have worked on over the years left over from my grandfather's days. I do 99% plumbing now, though I'm trying to learn more about hydronics.

      thanks,

      Chris
      Sounds like one or two seperate issues.

      First of all the valve should be open in normal operation. When filling a boiler system you bring it to pressure and then shut off the valve. Then you fire the system, bring it to full temp, and readjust the pressure level. This will also test the operation of the expansion tank.

      After the system is adjusted you would reopen the valve and leave it open. A blown expansion tank will allow excess pressure build up and also will a weeping boiler fill valve. The expansion tank typically will have 12 psi on the schrader valve. If water comes out the schrader...that is problem number 1. The boiler fill valve/boiler PRV, should also stop filling around 12-15 psi. If it doesn't...there is problem number2.

      Comment


      • #4
        Re: B&G FB-38 boiler fill valve

        If you want to find the btu input, you can time it by using the gas meter. Just make sure no other gas appliances are firing at the same time.

        Comment


        • #5
          Re: B&G FB-38 boiler fill valve

          Originally posted by Swade Plumbing View Post
          Should the valve that is piped in ahead of the valve be open or closed under normal operation?

          After reading the manual it seems that they suggest leaving that valve open for automatic refill, but in the pressure adjustment instructions, they say to close the valve once you have adjusted.

          The system in question is about 40 y/o and has an overhead steel overflow tank in the rafters. 3 zones with B&G series 100 pumps on each. Burnham boiler. I can't find the BTU or model # marked anywhere on it.

          After running the system for a couple hours, the pressure will creep up from 24 psi to 30 psi and trip the pressure relief valve. This sometimes occurs while the system is static too (none of the pumps are running).

          Thoughts or suggestions?

          This is one of only a handful of systems that I have worked on over the years left over from my grandfather's days. I do 99% plumbing now, though I'm trying to learn more about hydronics.

          thanks,

          Chris
          If pressure is creeping with a system not heating then the fill valve has a bad seat and needs replaced.

          Comment


          • #6
            Re: B&G FB-38 boiler fill valve

            Originally posted by Jones Mechanicals View Post
            If pressure is creeping with a system not heating then the fill valve has a bad seat and needs replaced.
            I was also thinking this was a possibility. I changed the filter screen last week. I have had the drain the expansion/overflow tank twice in the last week. The valve is not that old, but the house is pushing 85 years old and has all galvanized piping on the domestic water (including the supply to the boiler). I wouldn't be surprised if the some debris had gotten into the valve. I shut off the supply valve today in order to try and test this theory about the fill valve.

            thanks guys

            Comment


            • #7
              Re: B&G FB-38 boiler fill valve

              I would replace the fill valve and while you're at it drain the expansion tank.It is more than likely full.Also you might need a new relief valve ..
              ''Beer is proof that God loves us and wants us to be happy" Benjamin Franklin

              Comment


              • #8
                Re: B&G FB-38 boiler fill valve

                Originally posted by OLD1 View Post
                I would replace the fill valve and while you're at it drain the expansion tank.It is more than likely full.Also you might need a new relief valve ..
                soon to be done....and done (twice, will do it again) and done. Installed a new relief valve and temp/pressure gauge last week. New fill valve going in today. I tried to reset it as the lock nut was loose when I got there originally, but I think it's been weeping consistently and was causing the pressure to creep up (based on what others have suggested).

                Comment

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