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Storage tank noise?

Jlamb Member Posts: 14
Having an issue with a hotel domestic hot water storage tank making a noise that the employees say sounds like " a bowling ball being dropped" apparently it happens when they are doing laundry and seems only to happen later in the day when hot water usage is at its highest demand.

Quick overview to the best of my knowledge.

A.O. Smith 200 gallon storage tank fed by 4-540 ao smith tankless. Hot water output has not been an issue. 2" piping, building re-cir with check valve, mixing valve. Etc

They have a large washing machine can not remember the brand name but the directions of the machine says it can pull between 22-45 gpm on its rinse cycle. It's piped 1" both hot and cold with check valves and 1" water hammers. I have to believe this is a water expansion or water hammer issue but can't pinpoint it. I have not heard the noise anytime I have been there.

However I would think either the T&P valve or expansion tank would have some indication of this happening. Which isn't the case t&p has never blew off and expansion tank is exactly where it should be.

Maybe I'm missing something obvious?

Any help would be appreciated


  • Abracadabra
    Abracadabra Member Posts: 1,948
    pump issue? if the pump isn't circulating water to the tank sufficiently you may be getting water flashing to steam and you get water hammer?
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,337
    Hello: At a minimum, putting pressure gauges around the system; the type that has a needle pointing to the highest pressure experienced, might be a start. If their schedule is consistent, you might be able to be there when the "bowling ball drops". Your thermal expansion idea sounds like a good start, which the gauges should help prove. B)

    Yours, Larry
  • hot_rod
    hot_rod Member Posts: 22,262
    What is the water pressure? Sounds like either a check slamming or fill valve on the washing machine. High flow rates, high pressure and fast acting valves are sources.

    Hammer arestors should be checked, sized properly and installed at the device that causes the shock wave
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream