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Water Hammer (Domestic water)

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HH Pros:

Experiencing water hammer under the following conditions:

-Shower only;

-Individually controlled hot and cold water faucets;

-First open cold water supply (min flow)…no hammer;

-Next open hot water supply (moderate flow)…initially NO hammer. However, after less than one minute experience hammer. (quite visible vibrations at piping leaving gas hot water tank/heater);

-Finally…adjust flow at shower…hammer stops.

ANY and ALL input will be appreciated.

TY!

Comments

  • hot_rod
    hot_rod Member Posts: 27,116

    Could be a loose washer or disc inside the shower valve.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Larry Weingarten
  • Yellowlab
    Yellowlab Member Posts: 22

    Oh wow…was not aware. I will replace stems/washers. THANKS

  • hot_rod
    hot_rod Member Posts: 27,116

    Here is what a typical two handle faucet or tub/ shower valve stem assembly may look like.

    If the screw holding the washer becomes loose, or the rubber washer deteriorates, then that washer will chatter on the stem. Usually when you just start to crack open the valve.

    It is best to buy a kit that includes the new seat that the washer seals against. Some rebuild kits include the complete stem assembly and seat. That way all the washers and o-rings around the stem are new.

    Some ACE hardware stores carry an assortment of rebuild kits, Plenty of online sources for faucet rebuild kits.

    Screenshot 2026-01-16 at 11.09.26 AM.png
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Yellowlab
    Yellowlab Member Posts: 22

    Hot Rod - finally obtained two new cartridges…no more water hammer. Problem fixed!

    Thank you once for generously sharing your knowledge.

    Much appreciated.

    ethicalpaulHeatingHelp.com