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  • B&G 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.
    I posted this in the HVAC discussion, but thought that I might get more attention from the plumbing/heating guys over here. Moderators please delete one or the other if you see fit.
    thanks,

    chris

    OP:

    FB-38 1/2" valve
    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 boiler fill valve

    It should be shut off. You can follow the reasoning here.

    Heating Help - Heating Systems and then go to the wall and search for the thread
    sigpic

    Comment


    • #3
      Re: B&G boiler fill valve

      Originally posted by NHMaster3015 View Post
      It should be shut off. You can follow the reasoning here.

      Heating Help - Heating Systems and then go to the wall and search for the thread

      Thanks for link NHMAster. I've been told so many conflicting things over the years. the last 2 guys I talked to said it should be open. This article was really helpful and the whole site is very informative http://www.heatinghelp.com/article/1...ed-August-2011

      I've also been told that "normal" operating pressure range for a hydronic system should be 10-12 psi when "cold" and 20-25 psi when hot. But I've read that 15-18 psi is more or less "normal" too. What say you?

      thanks again,

      Chris
      Last edited by Swade Plumbing; 10-24-2011, 04:17 PM.

      Comment


      • #4
        Re: B&G boiler fill valve

        Originally posted by NHMaster3015 View Post
        It should be shut off. You can follow the reasoning here.

        Heating Help - Heating Systems and then go to the wall and search for the thread
        Please explain the reason it should be off.

        IMO it serves almost as a safety valve. If a boiler does not have circulation by loss of water it will begin boiling in the heat exchanger and the pumps will begin to fatigue without circulation and pressure. Just curious to your side.

        Comment


        • #5
          Re: B&G boiler fill valve

          I was taught it should be left on, and while Dan Holohan seems very knowledgeable, he was never a Heating contractor or any type of engineer.

          He expresses his opinion and nothing more.

          Comment


          • #6
            Re: B&G boiler fill valve

            Originally posted by Flux View Post
            I was taught it should be left on, and while Dan Holohan seems very knowledgeable, he was never a Heating contractor or any type of engineer.

            He expresses his opinion and nothing more.
            Seeing as it is nothing more than a PRV with a lower pressure setting, why not? If you go to a house with a system pressure far exceeding the PRV that unit will generally be changed. We don't tell the client it's ok just turn it off and only back on when you need water. The danger here is there will be noone there when it really does need water.

            It would be cool if a boiler had a solenoid valve attached to the main feed and linked to a pressure switch, but that would add another $300 to the install minimum.

            Comment


            • #7
              Re: B&G boiler fill valve

              Sounds to me, like the expansion tank is full, or the pipe going to expansion tank is clogged. Or if its a diaphram type expansion tank (extrol),the tank is bad. This will cause the pressure to increase, as boiler heats up.

              Comment


              • #8
                Re: B&G boiler fill valve

                Originally posted by Swade Plumbing View Post
                Thanks for link NHMAster. I've been told so many conflicting things over the years. the last 2 guys I talked to said it should be open. This article was really helpful and the whole site is very informative Heating Help

                I've also been told that "normal" operating pressure range for a hydronic system should be 10-12 psi when "cold" and 20-25 psi when hot. But I've read that 15-18 psi is more or less "normal" too. What say you?

                thanks again,

                Chris
                Anywhere from 10-25 can be normal. Current temp when reading the temp is important. Many of the new mod/con boilers have an internal pressure sensor that will drop out at 10psi. I recommend a cold temp of no less than 12-15 psi and I like the Caleffi boiler fill valve for this.
                Last edited by Jones Mechanicals; 10-24-2011, 09:04 PM.

                Comment


                • #9
                  Re: B&G boiler fill valve

                  Originally posted by Don the plumber View Post
                  Sounds to me, like the expansion tank is full, or the pipe going to expansion tank is clogged. Or if its a diaphram type expansion tank (extrol),the tank is bad. This will cause the pressure to increase, as boiler heats up.
                  It's a regular tank in the joists with a B/G tank air-flo valve on it. I had drained the tank before I refilled the system. When I was there last, the tank was full. I drained the tank today and the pressure gauge dropped to 0. I know that the line to the tank is not clogged as I have drained it twice already.

                  Originally posted by Jones Mechanicals View Post
                  Anywhere from 10-25 can be normal. Current temp when reading the temp is important. Many of the new mod/con boilers have an internal pressure sensor that will drop out at 10psi. I recommend a cold temp of no less than 12-15 psi and I like the Caleffi boiler fill valve for this.
                  Aquastat is set to 170 and I have verified that it is working. The T/P gauge was not working and I replaced it along with the Pressure Relief Valve when I changed one of the circ pumps (B/G 100) last week. When the system is running (1 or more of the pumps circulating) the boiler fires as necessary to keep the water at 170. I made an attempt to reset the fill valve (which I found the lock nut was loose and the valve was not at the factory setting of 12) and I left the inlet valve off for tonight to see how the system acts overnight.

                  This is the only multi zone system that I have worked on and getting it balanced after draining the system is driving me nuts! I'm trying to get my dad's old foreman to stop by (who maintained the system for about 25+ years) and give me a brainwash on its particular quirks.

                  Thanks guys.

                  Comment


                  • #10
                    Re: B&G boiler fill valve

                    Originally posted by Swade Plumbing View Post
                    This is the only multi zone system that I have worked on and getting it balanced after draining the system is driving me nuts! I'm trying to get my dad's old foreman to stop by (who maintained the system for about 25+ years) and give me a brainwash on its particular quirks.

                    Thanks guys.
                    Sounds like you have a vapor lock issue going on too. One thing for sure all boiler systems have their own personality. Stick with it...you'll get it.

                    Comment


                    • #11
                      Re: B&G boiler fill valve

                      Swade, does this boiler have a domestic coil on it?

                      Comment


                      • #12
                        Re: B&G boiler fill valve

                        No domestic water coil on this unit. Most older residential units are heating only around here.

                        Comment


                        • #13
                          Re: B&G boiler fill valve

                          If this were my house, I would take out the "in the ceiling" expansion tank and cap that line off.

                          - Take out the B&G automatic feed

                          - Install a "fill -trol" by Amtrol and be done with it.

                          Your water logged expansion tank days will be pretty much non-existent. No more draining the system because your expansion tank is full.

                          Amtrol- Fill-Trol

                          Comment


                          • #14
                            Re: B&G boiler fill valve

                            Ok, here's what's happened a couple of times with auto fill's left on. Due to the nature of most auto fill valves they don't get a lot of use so the screen plugs up or the piston freezes closed which sounds ok but.... Picture an older boiler with no low water cut off. The boiler begins leaking until it is empty but the burner keeps running which and then for reasons known only to god, the auto fill suddenly decides to let water into the red hot boiler and then......Baaaaaaam Not a common occurrence but it's happened often enough so that manufacturers of the valve all say to shut it off in their instructions.
                            sigpic

                            Comment


                            • #15
                              Re: B&G boiler fill valve

                              Originally posted by NHMaster3015 View Post
                              Ok, here's what's happened a couple of times with auto fill's left on. Due to the nature of most auto fill valves they don't get a lot of use so the screen plugs up or the piston freezes closed which sounds ok but.... Picture an older boiler with no low water cut off. The boiler begins leaking until it is empty but the burner keeps running which and then for reasons known only to god, the auto fill suddenly decides to let water into the red hot boiler and then......Baaaaaaam Not a common occurrence but it's happened often enough so that manufacturers of the valve all say to shut it off in their instructions.
                              I see the situation you are describing as being possible but Baaaaaam? The explosion is of course from rapid vaporization of water. What happened to the empty pipes of the system to absorb the steam and where did the relief valve go as it should be blowing off at 30 psi?

                              No doubt if a boiler did continue to fire the heat exchanger is most likely to crack anyway and the sudden impact of cold water would almost make it a certainty. The boiler's life is screwed either way. Now you have that same boiler with a working boiler auto-fill valved off and it's running hot and dry. Joe Blow homeowner walks down to the boiler, sees the fill valve closed off, and opens it...Baaaaam (if it happens) with a person in the room now. I would rather have the first option of a person not being in the same room.

                              Auto-fill valves tend to block up due to water chemistry and lack of flow. If the valve is closed off the lack of any flow is a guarntee. Part of an annual inspection on a boiler should be to test the valves operation. This is the number one safety in any system is annual service.

                              This is one we will have to agree to disagree as I will always leave this valve on in normal operation.

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