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Thread: Pump psi drops when vacuum (or Hayward) attached

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    rileypool's Avatar
    Join Date
    Mar 2009
    High Desert, California

    Pump psi drops when vacuum (or Hayward) attached

    Hi there. I'm new here, had my in-ground pool only 9 months, and would really appreciate some input.

    I don't know the gallons but it's about 30ft long with a deep end of say 7-8ft. Sorry I'm not being exact. Anyway: when the pump is running with a clean filter (DE) the psi is 8. When I run the vacuum, I notice more air coming into the pump basket filter (not much more) and the psi drops to zero.

    The vacuum works fine with the zero psi but the Hayward doesn't move. I am wondering what the problem could be?

    I gave the psi background because I thought maybe that was relevant? I have troubleshooted with the normal vacuum hose and the hayward hoses and they both behaved the same way. In my mind, that ruled out obstruction. I tried shortening the Hayward hose and found the pressure still dropped but only to 3, not zero. Is it something about the Hayward? My pump? I am clueless here and the local pool shop put me on hold for 30 minutes.

    If you can take me to school here, I'd be very grateful. Have a great day.
    46k gallon vinyl, Intelliflo VF, Quad DE 100, Autopilot DIG60, Raypak R405a, Bravo Fury Auto Cleaner

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    mas985's Avatar
    Join Date
    May 2007
    Pleasanton, CA

    Re: Pump psi drops when vacuum (or Hayward) attached

    First, welcome to TFP.

    The PSI drop in the filter indicates a significant drop in flow rate. Combining this with the air in the pump basket would indicate a high restriction in the water flow on the suction side of the pump. This could be a blockage of some sort in one of the cleaner lines.

    Normally, a suction cleaner will drop the PSI somewhat but down to 0 PSI is not normal and could create cavitation in the pump. Because the suction is so high, air is being drawn into the pump basket via the lid and valves. I would double check the lines & valve settings again to make sure that they are clear of debris. Check the cleaner head as well. Also, it could be in the line between the pump and where the hose connects to the plumbing.
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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