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noisy boiler

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The guys talking about the ZV's are probably on the right track. A boiler jacket "thud" will not resonate through the piping (duh). Are there an other variables on the job regarding water flow, i.e. blending/temp. control valves? You may also want to check the hanging/support of the piping/radiation itself; bell hangers especially (if tight)may cause a noise as piping expands/contracts. This movement cannot be halted and must be accounted for (cast iron baseboard gives such a noise). Hope this helps.


  • Ryan_14
    Ryan_14 Member Posts: 8
    Noisy Boiler

    We recently added two zones to an existing system. When we started the project the boiler had some lime build up (that's another story in its self) Anyway we ran cleaner through it and it seemed to remove most of it. The boiler stopped banging during the run cycle.
    We can no longer hear lime in the boiler, but sometimes when the burner is running, the HO gets a loud bang from the unit. I am thinking more lime, but it just doesn't sound like it. Does not bang every cycle and only does it once. In my 25 years on the job, I have not had a boiler do this before.
  • Ken_40
    Ken_40 Member Posts: 1,320
    I had a similar one once.

    It was a large piece of sheet metal jacketing on the side.

    As the metal heated from the "on" cycle, the geometry was such and the capture screws just snug enough to make a distinctive "boom." Happened randomly, but always when the heat was comiong up and close to the end of the "on" cycle.

    The fix? Loosened the center-most sheet metal screw 1/4 turn (allowing a trace of slippage during expansion/contraction cycles).

    For what it's worth, it was a W/M EG boiler.


    Did you add thos zones using circs or zone valves?

    If zone valves, honeywell, taco or erie? (or other)
  • Ryan_14
    Ryan_14 Member Posts: 8
    Honeywell zone valves

    We used honeywell zones valves on the return.
  • I think you will find

    the banging is a zone valve closing, not the boiler.

    This problem has been addressed her very extensively.
    The problem occures when you have too much flow through a single valve making it close too fast. More like a water hammer type banging. Either one of your new zones is opening and closing on it;s own or it is the last to close.

    Check to see if this is what you are experiencing.
  • Eric Smith
    Eric Smith Member Posts: 4

    Come on guys - sounds to me like it's to much air in the lines not the boiler - put in an air eliminator like: http://www.houseneeds.com/shop/HeatingProducts/HydronicHeating/AirVents/spiroventbuypage.asp


  • Great idea

    to use on all wtaer systems.

    But how do you figure this is what is causing the banging that has been explained here????

    Please explain, maybe I can learn something.
  • Ray Landry_3
    Ray Landry_3 Member Posts: 94

    Sounds to me like this guys just trying to sell spirovents on his site...
  • Ryan_14
    Ryan_14 Member Posts: 8
    noisy boiler

    We installed a honeywell air separator when we installed the zone valves. The zone valves never close when the noise occurs.
  • WOW


    The Honeywell/Sparco vent works great.

    When the noise happens, is there any way for you to be looking atthe flame? Is it a BANG or a Thump?

  • Ryan_14
    Ryan_14 Member Posts: 8
    I was not watching the flame, but

    I was not watching the flame, but I could hear the burner firing. The noise, its like someone whacks the side of the boiler. The most of the noise is really from the pipes shaking. First the bang from the boiler immediately followed by the pipes shaking.
  • Mitch_4
    Mitch_4 Member Posts: 955
    Go with the metal expansion

    Happens in forced air ductwork often. especially old stuff. Loosen some panel screws so it flexes freely.
  • Tony_23
    Tony_23 Member Posts: 1,033
    What boiler

    What make & model is it ?

    Honeywell "Supervent" has been nothing but trouble for me. Even to the point of removing them and installing the Spirovent that I should've to start with.

    Honeywell has a new ZV with a cetrifugal brake in the motor to alleviate hammer from quick closing.
  • Ryan_14
    Ryan_14 Member Posts: 8
    Weil Mclain

    Its a gas fired Weil Mclain, Sorry, I don't have the model. Just a standard gas boiler, standard vent, about 12 years old.
  • Ken_40
    Ken_40 Member Posts: 1,320
    I still suggest it may be

    sheet metal jacketing "popping" when "trapped" by the cabinet screws and flexing!

    Loosen all the cabinet screws one half turn and see what happens. Better yet, the HO may be trusted to do this?

    The noise sounds identical to a marching band type bass drum dull thump. Nearby pipes, especially those touching the cabinet, will "telegraph" the sound, adding their own harmonics.

    Like the annoying "frog clickers" that we had as kids, sheet metal when under stress, can make a loud flex pop/noise. Imagine he little 3/4" X 1" noise from the finger clicker/popper dropping about 10 octaves for sheet metal 24" X 40"?

    If you've already ruled out combustion, zone valves, etc., Think large panels of sheet metal lad!
  • Uni R_3
    Uni R_3 Member Posts: 299

  • Uni R_3
    Uni R_3 Member Posts: 299

  • Handy_2
    Handy_2 Member Posts: 2
    loud boiler, one zone doesn't work

    We recently moved into a house with gas hot water (baseboard) heat. Sometimes the bioler sounds as if someone is hitting it with a hammer. This happened this morning and now one zone does not get hot water (actually, only the first of eight baseboards gets heat.) I felt the pipes and the supply pipe is warm just until 1-2 feet from the first baseboard; after that, it's cold. Any suggestions on problems or solutions? We're new to this type of heating and would like to make repairs without expensive house calls. Thanks!
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