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Thread: Booster pump losing prime.

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    Booster pump losing prime.

    I have a JetVac cleaner with VS Whisperflow main pump and Pentair LA01N booster pump that tends to have trouble priming sometimes. If I understand correctly the main pump is always passing some water through the front intake of the booster pump, through the pump and out through the booster return line. Then when the booster pump kicks on it should run and drive higher volume through to the cleaner making it run.

    All that said (assuming that's correct?), I disconnected the booster return line with the main pump off. Then turned on the main pump and had good water flow out the booster return, until the pump slowed down to normal speed. It has a feature where when it is first turned on it turns higher RPMs for a minute, then settles down to the programmed RPMs.

    Once it "idled down", I had no flow coming out of the booster return line. Does that sound correct? Or should there always be some flow out the booster return?

    Thanks,
    GM
    GM

    ~45' x 15' free form (9.5ft deep end) pool; Pentair 4 speed pump w/ JetVac cleaner & booster pump; DE FNS 60 filter; Intellichlor SWG; Diamondbrite finish.

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    Re: Booster pump losing prime.

    The pump only has one speed. It does not idle up or down.

    Sounds like maybe air in the lines.
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    needsajet's Avatar
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    Re: Booster pump losing prime.

    Just to be clear, you're saying that with the booster pump turned off:

    When your main variable speed pump starts on high speed, some water is pushed through the booster pump circuit.

    When your main variable speed pump slows down to a slower programmed speed, no water is pushed through the booster pump circuit.

    Is that right? Is there a problem occurring as a result?
    12k IG salt; glass beads in plaster; K-2006C, K-1766, K-1106 and CCL test kits; Pentair Eco800 1.2HP VS; Zodiac SWCG 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; Other family pools 10K SWCG and 15K on liquid; PoolMath app subscriber; | Tips for New Members to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    mas985's Avatar
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    Re: Booster pump losing prime.

    Quote Originally Posted by gm View Post
    VS Whisperflow
    Do you actually have an Intelliflo VS?

    Once it "idled down", I had no flow coming out of the booster return line. Does that sound correct? Or should there always be some flow out the booster return?
    Depends on the pressure at that point. Pressure drops with lower RPM so if the booster line is elevated a good distance above the pool water, water may not come out of the line if the resulting pressure is too low. In fact, it could get sucked in instead.
    Mark
    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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    Re: Booster pump losing prime.

    Thanks for the replies guys.

    When I say idles down, I mean the main pump (yes it's Intelliflow VS 4 speed). Neesdajet, that's right when the main Intelliflow goes to programmed speed (lower RPM) then no flow comes out of the booster return/outlet it only comes out at higher RPMs. I was wondering if that's causing the loss of prime in the booster pump.

    Mas98, pressure is at about 12 PSI when the main pump is at lowest programmed speed. I don't think the programmed speed (1950 RPM) is too low as I've never changed it since the original pool install about 8 years ago.
    GM

    ~45' x 15' free form (9.5ft deep end) pool; Pentair 4 speed pump w/ JetVac cleaner & booster pump; DE FNS 60 filter; Intellichlor SWG; Diamondbrite finish.

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    mas985's Avatar
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    Re: Booster pump losing prime.

    Quote Originally Posted by gm View Post
    Mas98, pressure is at about 12 PSI when the main pump is at lowest programmed speed. I don't think the programmed speed (1950 RPM) is too low as I've never changed it since the original pool install about 8 years ago.
    That's at the filter gauge correct? The fitting is down stream from that.

    Also, have you tried to disconnect the booster inlet to see if water comes out of that hose?

    There is usually a filter in the booster inlet that can get clogged.
    Mark
    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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    Re: Booster pump losing prime.

    Yes, that was on the filter gauge. Haven't tried disconnecting the booster inlet, I'll try that and see what I get....when/if it ever stops raining!
    GM

    ~45' x 15' free form (9.5ft deep end) pool; Pentair 4 speed pump w/ JetVac cleaner & booster pump; DE FNS 60 filter; Intellichlor SWG; Diamondbrite finish.

  8. Back To Top    #8

    Re: Booster pump losing prime.

    I thought that you meant that the booster was changing speed. The main pump makes sense since it goes from priming mode to run mode.

    If the system is free of air, the booster should prime even with little to no flow.

    12 psi at low speed indicates that the filter probably needs to be broken down and cleaned.
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  9. Back To Top    #9

    Re: Booster pump losing prime.

    Well, looks like JamesW was right, finally got a chance to clean the filter and things are running fine now. Thanks everyone!
    GM

    ~45' x 15' free form (9.5ft deep end) pool; Pentair 4 speed pump w/ JetVac cleaner & booster pump; DE FNS 60 filter; Intellichlor SWG; Diamondbrite finish.

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    Re: Booster pump losing prime.

    Good job. Thanks for the update.
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