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  1. #1
    Join Date
    Oct 2005
    Location
    Minneapolis
    Posts
    8

    I've got a new boiler installed with a 70-year old gravity system. This has a Taco 007-series pump for circulation. Everything is hard-plumbed together with galvanized pipe.

    I've noticed that sometimes the pump makes the house hum. Really odd as it'll be noticable in some places but not other. Also it'll get the regular water going too sometimes. Really weird.

    The pump seems to be running smoothly as it doesn't shake and it isn't loud by itself.

    I've done some searching and can't find any products designed to help with this.

    Any ideas?

  2. #2
    Join Date
    Jan 2004
    Posts
    108
    First, confirm that it's the pump by turning power to the pump off, then on when it's making noise. Once you are sure it's the pump, you have some options:

    1) Something, somewhere in the house has a resonant frequency that matches a pump frequency. Find that something and do something to stop the vibration, such as clamping it down.

    2) Something, somewhere in the house has a resonant frequency that matches a pump frequency. Change that pump frequency. The frequency you want to change is the blade passing frequency, which you can change by changing pump speed or by changing to a different pump with a different number of blades in the impeller.

    3) You can try isolation by adding sections of rubber hose before and after the pump. This might help.

    4) Study up on Tuned Vibration Absorbers and Tuned Mass Dampers. The first two approaches are the better way to go, but this could be more fun if like those sort of gadgets.

    5) Maybe you have a bad pump with a defective impeller. Try buying a new pump. This is unlikely, but you would then have a spare pump on hand.

  3. #3
    Join Date
    Oct 2005
    Location
    Minneapolis
    Posts
    8

    Thanks, engineerguy. Me engineer guy, too.

    The pipes that shake are behind the walls and ceilings, of course!

    Rigging an external harmonic damper would be a lot of trial-and-error work with materials I don't have. Low chance of success, too.

    I was hoping that someone would know of an isolation kit for hard piping. I was thinking that a new style system with plastic lines would not have this problem. Or that there was a damper kit available.

    The pump seems to be fine itself. A low hum at the source but just right for the water pipes somewhere.

  4. #4
    Join Date
    Apr 2004
    Location
    where you at?
    Posts
    3,359
    are you referring to pipe spring-hangers or neoprene?
    there are a variety of products available.

    check-out Kinetics.

    are you sure it's a pipe resonance?
    is the unit well isolated? that may be the first place to start with the most 'direct solution', as compared to measuring the transfer function of the major structural elements near the unit (as eluded-to above)

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