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Thread: check valve before or after pump

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    check valve before or after pump

    I have another thread just below detailing the leak issues and priming issues I am having with a newly installed whisperflo pump. In my research on hear, I'm starting to think that I need a check valve installed to help keep water in the basket after the pump is shut off since the equipment is slightly elevated above the pool. I have purchased a check valve but don't know if it should be before or after the pump? The pump is leaking at the bottom, so until it gets fixed I will not be able to maintain prime but even when there are no leaks the water rushes back in the plumbing and out of the basket at shut off and takes a little time to prime back up. I assume that a check valve will help this. I have one check valve installed currently after the heater and before the chlorinator as it was instructed in the heater install. Attached is a picture of my equipment. Thanks!!

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    Re: check valve before or after pump

    another picture

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    borjis's Avatar
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    Re: check valve before or after pump

    The check valve should be in line between the pump output and the input of the filter.

    but something is different in the first top picture.

    it looks like a check valve or is that a union coming out of the top pipe (on the pump)

    It's missing in the 2 lower photos. which photo is current?

    Is your pump leaking now because of running it without it priming?
    The pump motor seal won't last long if the pump runs dry.
    16x32 IG Vinyl, 13,000 Gals. Hayward S-244T sand filter, SP2810X15 pump
    (1.5 HP motor) Raypak PR266AEN (266k btu) gas heater. TF-100 Test Kit.
    Dolphin E10 Cleaning Robot.

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    Re: check valve before or after pump

    Thanks for the reply. I see what you are talking about on the difference. The top picture was taken before the new pump was installed (last month). When they installed the new pump they used unions on each side for easier access in the future. So I need the check valve on the long pipe between the pump and the inlet at the filter and not in the short line between the skimmers and the inlet at the pump correct?

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    borjis's Avatar
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    Re: check valve before or after pump

    yes correct, you want it between the pump and the filter.

    I just had a new one installed last month.
    16x32 IG Vinyl, 13,000 Gals. Hayward S-244T sand filter, SP2810X15 pump
    (1.5 HP motor) Raypak PR266AEN (266k btu) gas heater. TF-100 Test Kit.
    Dolphin E10 Cleaning Robot.

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    Texas Splash's Avatar
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    Re: check valve before or after pump

    For what it's worth, I have seen check valves in various locations based on the hardware used in the system, elevation of the pad, and specific application to be achieved. You'll see many such discussions on this forum. Just a couple examples:
    - As noted by borjis above, a check valve between the pump and filter could be used by some who don't want their filter contents to flow backwards to the pump. Perhaps even more valuable for DE and sand filter applications.
    - Some have a check valve before the pump as to not lose prime at the basket when power is turned-off

    The need for a check valve may also be dependent upon the availability of other pre-existing 2/3-way valves that may used to achieve specific results (i.e. suction/pressure side isolation). I guess at the end of the day, every pool can be different based on all of those factors. Just make sure that any new valve you are considering splicing into your system will give you the end result you hope to achieve.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Re: check valve before or after pump

    Thanks Texas Splash, I appreciate the insight. I am trying to accomplish not losing prime when the pump shuts off. Now I am really confused. I have 2 2 way valves (I think) that bring water into the pump. One from the skimmers and one from the main drain. The valves are always set how they are in the pictures above. I guess I am not sure how to proceed. If I place the check valve between the pump and filter, then the water will still be able to flow out of the pump and to the filter, correct? But on the other hand, if it is before the pump, the water can still flow to the filter and out of the pump.

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    borjis's Avatar
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    Re: check valve before or after pump

    Either way should work, but if you are installing the check valve BEFORE the pump and after the main drain & skimmer valves
    in order to hold prime....that;s not really solving the holding prime problem.

    I would almost speculate if you did it that way, yes the pump basket would probably stay full, but would empty quickly
    when turned on since the problem of not holding prime is still there before the check valve.
    16x32 IG Vinyl, 13,000 Gals. Hayward S-244T sand filter, SP2810X15 pump
    (1.5 HP motor) Raypak PR266AEN (266k btu) gas heater. TF-100 Test Kit.
    Dolphin E10 Cleaning Robot.

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    Re: check valve before or after pump

    Thanks again borjis. I think I get it now. The pressure from everything past the check valve towards the filter and existing lines would close the flap in the check valve therefore keeping water in the basket of the filter.

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    Re: check valve before or after pump

    As an update I think I figured out what was causing all my trouble. Our build came with an ozone system. The hose that is connected to the valve with the ball in it had a bad connection which was causing me to lose prime every day. Been like that from day one, I just didn't know any different. I actually spoke to the Pentair local rep about all the issues I was having and he recommended checking the ozone system out. He stated that he's seen lots of issues with the ozone equipment on their pumps. He also said that if the pump loses prime when off, when the pump/ozone kicks on, until it primes the unit is just pumping ozone gas into the basket delaying prime and also causing seal issues. I uninstalled the ozone system and have not lost prime one time since. The basket stays completely full! Looks like I will be learning the TFP method asap

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    Texas Splash's Avatar
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    Re: check valve before or after pump

    Good for you! Always good when another system mystery is solved. Have a great night.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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