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Banging/Knocking hot water baseboard heat

Well I have loud pipes. For the last 12 years. My solution has been to cut the heat off at 11 pm and turn it back on at 7 am. Now that we are selling the house we are trying to fix it. Its not a ticking like the fins rubbing. Its a loud knocking that is very quick, one after the other, then slower, then slower, then stops. I've combed the fins, we've bled the system (although I do note that there are no upper level bleeders, must be done from the basement). I've chiseled out around the pipe, I've lifted the pipe, moved the pipe, left, right, up down. Kicked it in frustration several times. Shoved plastic shims in the floor holes. I've changed the temp on the boiler up and down, nothing. Finally we opened up the ceiling underneath where we thought the banging was coming from. Seemed ok, but we installed an accordion joint. Still nothing. I'm going bonkers. I really don't want to tunnel out my entire living room ceiling. Its two zones, this is the second floor. The first floor is wonderful. The second is the issue. It supplies plenty of heat, just loudly. Also I've noticed that when the system is cold, it doesn't really happen. It happens when the system is cycling on and off. So for example in the morning when it has been off all night, I turn it on and its ok, but then when it cycles off and then back on it bangs every time. The two zones each have their own circulator pumps. Is there anything I can do beyond ripping out of my ceiling to expose the pipe? Anything that can be installed to dissipate the noise? Help? Anything?

Comments

  • Ironman
    Ironman Member Posts: 6,579
    Are there any zone valves on the system?

    How about posting some pics of the boiler and its near piping from a few feet back?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • bcantrell17
    bcantrell17 Member Posts: 10
    Thanks for your response. I'm not sure. Aren't zone valves for if I don't have individual pumps per zone? I'll take some pics the best I can, not a lot of room in the utility room. Be right back.
  • bcantrell17
    bcantrell17 Member Posts: 10




  • Jamie Hall
    Jamie Hall Member Posts: 17,111
    That is classic expansion noise. Really classic! The solution is to find the pipes which are rubbing on something as they expand, and either shift the hangers slightly so the don't rub or slip a piece of polyethylene -- a plastic milk jug is ideal -- between the pipe and whatever it is rubbing on. Should fix it right up. However, if you can't get at the pipe you may be out of luck.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    bcantrell17
  • bcantrell17
    bcantrell17 Member Posts: 10
    That's what I was afraid of. Thanks for confirming. Unfortunately it will require ripping out the entire living room filing to find it! Thanks again.
  • Ironman
    Ironman Member Posts: 6,579
    Can you get the full model number off of the circulator's data tag? It's on the electrical cover of the pump.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • HVACNUT
    HVACNUT Member Posts: 4,203
    edited February 2017
    Like Jamie said, definitely sounds like expansion noise. You don't hear it on the first cycle in the a.m. because it's a cold start aquastat and the circ runs pushing cold water through the loop, then slowly heats, avoiding that rapid cold to hot expansion that you get on later cycles. The easy fix is... play some Metallica, loud.
    bcantrell17
  • MikeL_2
    MikeL_2 Member Posts: 292
    You could try constant circulation with outdoor reset including a low loss header or another type of primary/ secondary near boiler piping. Outdoor reset would reduce the rapid expansion that occurs when ambient temperature water is replaced by high temp boiler water........
    bcantrell17
  • bcantrell17
    bcantrell17 Member Posts: 10
    Iron Man, the # is Taco 007-F5
    Ironman said:

    Can you get the full model number off of the circulator's data tag? It's on the electrical cover of the pump.

  • bcantrell17
    bcantrell17 Member Posts: 10
    HVACNUT, that has been the other half of my band-aid solution!
    HVACNUT said:

    Like Jamie said, definitely sounds like expansion noise. You don't hear it on the first cycle in the a.m. because it's a cold start aquastat and the circ runs pushing cold water through the loop, then slowly heats, avoiding that rapid cold to hot expansion that you get on later cycles. The easy fix is... play some Metallica, loud.

  • HEATON
    HEATON Member Posts: 117
    have you checked the temp leaving the boiler? I had one that was making steam cause the controls failed and gauge was unreliable? Definate agree w/constant circ with or without O>D> reset. Things that go bump in the day, " Scarey" john
    bcantrell17
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 10,328
    Shut the boiler off and just run the circulators if you can. Is it quiet?? This will tell you if the noise is related to changes in water temperature or not.
    bcantrell17
  • Mike
    Mike Member Posts: 94
    Have you checked the air charge, in the expansion tank? Had a system doing the same as yours, the tank had lost it's charge. Pumped it back to the proper pressure, and all was quite.
    bcantrell17
  • bcantrell17
    bcantrell17 Member Posts: 10
    Yeah, I've ran it at the lowest temp on the boiler and it still banged. Thanks.
    > @HEATON said:
    > have you checked the temp leaving the boiler? I had one that was making steam cause the controls failed and gauge was unreliable? Definate agree w/constant circ with or without O>D> reset. Things that go bump in the day, " Scarey" john
  • bcantrell17
    bcantrell17 Member Posts: 10
    I'm not sure if I can do that... I'll give it a shot. Thanks

    > @EBEBRATT-Ed said:
    > Shut the boiler off and just run the circulators if you can. Is it quiet?? This will tell you if the noise is related to changes in water temperature or not.
  • bcantrell17
    bcantrell17 Member Posts: 10
    I thought the pressure was fine, but I will check the expansion tank. Thanks.

    > @Mike said:
    > Have you checked the air charge, in the expansion tank? Had a system doing the same as yours, the tank had lost it's charge. Pumped it back to the proper pressure, and all was quite.
  • bcantrell17
    bcantrell17 Member Posts: 10
    This is a very technical response! I will have to forward it to someone that understand this better than I. Thanks for your response!!

    > @MikeL said:
    > You could try constant circulation with outdoor reset including a low loss header or another type of primary/ secondary near boiler piping. Outdoor reset would reduce the rapid expansion that occurs when ambient temperature water is replaced by high temp boiler water........