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Thread: Hayward H250ED2 "hammer sound" on startup

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    Hayward H250ED2 "hammer sound" on startup

    I have a H250ED2 pool/spa heater that was installed 2005. Upon starting it up yesterday, after a few seconds it began making a hammering sound, lots of banging. Could it be I have an issue with the bypass valve or T-stat? Does anyone know when Hayward began using the thicker plastic baffle in these units?
    If it needs a bypass valve kit, is it something that I could probably do myself?? I have converted my pool 3 yrs ago to a SWG doing all work myself including wiring...I have replaced my pool pump myself so I have average to above skills.


    Pool Specs: IG Plaster, approx 34 feet long and 14 feet wide, Sand Filter, Installed at least 15 years ago we believe

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    In the Industry
    ps0303's Avatar
    Join Date
    Jul 2011

    Re: Hayward H250ED2 "hammer sound" on startup

    Broken bypass. Pretty much all of the ED2's were made with the old thin style bypass.

    Hayward Broken Bypass Video - YouTube

    A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you.

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    txnole's Avatar
    Join Date
    Aug 2014
    Amelia Island, FL

    Re: Hayward H250ED2 "hammer sound" on startup

    Probably a broken bypass, but - for grins - play with the valve before your heater. We had the same issue on low flow.
    COMPLETED BUILD THREAD - 15'x29' rectangular offset shotcrete pool; 14,100 gal; 5'x7' raised spa with 400k btu fire feature; 7' spillover; 25' leuder stone raised bond wall w/waterfall; Pentair SWG; Pentair VS (pool); Pentair 3/4hp feature pump; 1hp spa blower; Pentair Cartridge filter; Pentair “Easy Touch 8” wireless; Dolphin Oasis Z5 robot; Solar Hydronics iSwim solar panels; Mansard Screen Enclosure; walnut travertine deck; 1 very happy kiddo.

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