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Thread: Changed multiport; now air in lines & pump says "obstruct'n"

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    ajgiii's Avatar
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    Changed multiport; now air in lines & pump says "obstruct'n"

    Hi All!

    Problem: Air in system

    Question/Theory: New multiport too small, creating too much suction head, causing air getting sucked in through valve body pieces?

    Background:
    Just replaced my old multiport due to internal damage. Couldn't find one of the same make, so bought a different brand (Hayward Variflo). This new multiport is physically smaller than the old one, but uses the same piping size (1 1/2").

    The multiport's drain port leaks water in a slow drip, even after ensuring the spider gasket was seated (Hayward actually glued it in place). There is an ooze leak from the return port (the multiport has threaded fittings; apparently, I didn't get enough PTFE on that connection). PTFE on the other ports is smooth at the fitting-to-multiport (i.e., no indication of water leaks out or air leaks in).

    After a few minutes running, the system gets a lot of air in it--I keep having to bleed the filter. This didn't happen prior to replacing the multiport. If I don't bleed, the pump shuts off and says there's an obstruction (too bad it doesn't say "suction" or "return" location). This didn't happen prior to replacing the multiport.

    In Pumping 101, it says if there's too much suction head, the system will draw air in through valve body parts (like between the top and bottom of the valve).

    Evidence of this phenomenon: when I changed from an open drain connection to a plug in the multiport drain port, the kW meter on my pump dropped noticeably (but air still gets in the system).

    The more I write and think about it, it sounds as if the smaller multiport created excess suction head, so I need to change the multiport to a physically larger one.

    Thoughts?

    Best to all,
    AJGIII

    30K gallon, inground w/integral spa, blue/gray plaster; Pentair Intelliflo pump, D.E. filter, Ultraflow UV generator, Hayward tab chlorinator, Polaris 360, Raypak propane

    "As long as you are in the seat...Make a Difference"
    ---Captain James T. Kirk, circa 2293

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    Mod Squad Bama Rambler's Avatar
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    Re: Changed multiport; now air in lines & pump says "obstruct'n"

    Unless your system is plumbed backward the multiport can't leak air in when the pump is running. Air has to come from the suction side. I suspect a coincidence in changing the multiport and the air getting in the system.

    The most common places for air to get into the system is the pump strainer basket lid or the skimmer sucking it in due to the weir not working correctly or the water level being a little low.

    Now, if your MP valve is new and it's leaking it should be under warranty and should be repaired or replaced. Even if it's not the cause of the air it still shouldn't leak when the pump is running.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Changed multiport; now air in lines & pump says "obstruct'n"

    Just reinforcing bama's post....multiport is on the pressure side of the system and cannot suck air. Your air leak is somewhere between the impeller and the skimmer(s)
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    ajgiii's Avatar
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    Re: Changed multiport; now air in lines & pump says "obstruct'n"

    Hi Guys

    Thank you for responding. One of the first things I checked was pool water level. It is fine. However, I recall that my skimmers haven't had the draw they normally do and was going to go out just now to vacuum the lines to see if I get anything out of them.

    My next step was to check the impeller for something caught in it. And, I'll triple check my pump/return lines to the multiport to ensure they are correctly plumbed. After that, I'm stumped.

    Will report back.

    Best regards.
    AJGIII
    30K gallon, inground w/integral spa, blue/gray plaster; Pentair Intelliflo pump, D.E. filter, Ultraflow UV generator, Hayward tab chlorinator, Polaris 360, Raypak propane

    "As long as you are in the seat...Make a Difference"
    ---Captain James T. Kirk, circa 2293

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    ajgiii's Avatar
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    Re: Changed multiport; now air in lines FOLLOW UP

    I tightened the plugs on the multiport that cover unused ports. While these plugs did have new o-rings in place, and they were not leaking, tightening them significantly reduced the air in the lines.

    This agrees with what is presented in the "Pumping 101" discussion on this site!!!

    Way to go TPC!!!
    30K gallon, inground w/integral spa, blue/gray plaster; Pentair Intelliflo pump, D.E. filter, Ultraflow UV generator, Hayward tab chlorinator, Polaris 360, Raypak propane

    "As long as you are in the seat...Make a Difference"
    ---Captain James T. Kirk, circa 2293

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