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Thread: Mysterious pressure increase when changing between returns and waterfalls

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    Mysterious pressure increase when changing between returns and waterfalls

    I recently noticed that when I switch the flow of water from 100% to the in pool returns, to 100% to the waterfalls, the pressure reading on my Hayward DE4820 filter jumps from about 18PSI to almost 28PSI. Attaching a video. Any idea what might cause this? Do you hear that noise before I switch the valve? I think it comes from the mutliport valve. Sounds like sand bouncing around in there, but I'm guessing it's actually air?

    Also, in case it's related, I've noticed lately that when I turn the pump off, there's a surge of pressure that forces water to squeeze out from the lid of pump strainer. The gasket on the lid is a Hayward part, is well lubed, and was recently replaced.

    http://youtu.be/R7QdJDgoL8w
    16k gal, IG plaster, Hayward 48sqft DE Filter, Hayward Max-Flo VS w/Pentair booster, Polaris 280 cleaner, installed 2003

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    JasonLion's Avatar
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    Re: Mysterious pressure increase when changing between returns and waterfalls

    The pressure change is normal. Each different plumbing run has it's own unique pressure, which depends on pipe size, pipe length, number of fittings etc.

    Everything else you describe sounds like you are getting air drawn into the system somewhere. Take a look at this article in Pool School for details on where to look for air getting in.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Mysterious pressure increase when changing between returns and waterfalls

    Thanks JasonLion! If I'm seeing the water splash out from the pump basket lid, does that mean that's the source of my air leak? Or could air still be coming in somewhere else and then forcing the lid up when the pump is shutoff?

    I'll check all the other typical spots in the morning when I can see better.
    16k gal, IG plaster, Hayward 48sqft DE Filter, Hayward Max-Flo VS w/Pentair booster, Polaris 280 cleaner, installed 2003

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    Mod Squad tim5055's Avatar
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    Re: Mysterious pressure increase when changing between returns and waterfalls

    Quote Originally Posted by BCinAustin View Post
    Thanks JasonLion! If I'm seeing the water splash out from the pump basket lid, does that mean that's the source of my air leak? Or could air still be coming in somewhere else and then forcing the lid up when the pump is shutoff?

    I'll check all the other typical spots in the morning when I can see better.
    The pump basket lid should be sealed, so that is what I would be looking at....
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Mysterious pressure increase when changing between returns and waterfalls

    I agree that it's air being drawn in on the suction side. The noise is probably due to the air causing cavitation in the system. The reason the sound is reduced at higher pressure is that the water is going slower and the higher pressure reduces cavitation. I think that there is cavitation on the pressure side where fast moving water creates low pressure around sharp angles.

    If water squirts out when the pump is turned off, that's a likely spot for an air leak.

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    Re: Mysterious pressure increase when changing between returns and waterfalls

    Quote Originally Posted by JamesW View Post
    If water squirts out when the pump is turned off, that's a likely spot for an air leak.
    Thanks everyone. I recently replaced the o-ring on the lid with an original Hayward part. I do notice the lid seems to twist on alot easier than it did with the old o-ring (which was pretty well worn and had lots of "texture" from years of suspected unlubricated use by the previous owners). I took the o-ring out this morning and wiped it down (in case I'd somehow over lubed it) and then put it back into the lid lightly (hoping to let the suction of the system seat it properly).

    That seems to have diminshed the amount of water that is pushed out when I turn off the pump, but it definitely didn't stop it altogether. I definitely never recall this happening with the older o-ring. It seems like it started happening around a month ago, after I'd already replaced the o-ring, but when I noticed that our filter pressure had risen to a point that a backwash was needed. I figured that maybe after backwashing, the decrease in overall pressure might help, but it doesn't seem to have done anything. I checked both the plugs on the pump this morning. I re-lubed their o-rings and reinstalled. There does not appear to be any leakage around them (air in or water out). If my ears are telling the truth, I hear a faint air leak (sucking in) in the vicinity of the lid once the pump is off. I also then see/hear a bunch of air bubbling into a see-through port on a pipe that runs out from my multiport valve to the pipes that feed my returns/waterfalls. I have manually released all the air out of the DE filter.

    Not surprisingly, I have also noticed that the pump is not holding prime. After it's been off for a while, the water level in the basket vessel has dropped at least by half.

    Could it be that the lid itself is now defective? Should I posted a video of the pump lid leaking water and bubbling port near multi-valve when I shutoff the pump?

    Could it be the gasket inside of my multiport?
    16k gal, IG plaster, Hayward 48sqft DE Filter, Hayward Max-Flo VS w/Pentair booster, Polaris 280 cleaner, installed 2003

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    Mod Squad zea3's Avatar
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    Re: Mysterious pressure increase when changing between returns and waterfalls

    You can rub a few soap bubbles around the lid and see if it is getting sucked in while the pump is running. Has the pump ever run dry for any length of time?
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    Re: Mysterious pressure increase when changing between returns and waterfalls

    I don't believe it's ever run dry. Usually it keeps some water and when I've watched it recently it does manage to achieve prime relatively quickly and stay full while on. I really don't see hardly any air through the pump lid while it's running, after it's full (but I guess if it's a small leak, it could be well blended and later cavitating as someone was speculating).

    I'm starting to wonder if I've just got the wrong o-ring. I sent my info to Hayward (Hayward Northstar pump (SP4015NS), serial #: 630D33) and they said I needed SPX4000TS. That's exactly what I bought http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1. But it's pretty notable how much easier this one twists on.

    With the old one, I couldn't imagine there being enough play in the lid for it to raise up and let any water out.

    I'll try the soap trick and see if I can detect any sucking.
    16k gal, IG plaster, Hayward 48sqft DE Filter, Hayward Max-Flo VS w/Pentair booster, Polaris 280 cleaner, installed 2003

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    Re: Mysterious pressure increase when changing between returns and waterfalls

    Update from Hayward. They've confirmed that I've got the right ring, but admitted that my Northstar has a lot of power and can sometimes create enough pressure to budge the lid on start and shutoff. As a courtesy, they're going to send me a different ring that might create a tighter fit at the lid. I'll keep everyone posted. Thanks as always for the help.
    16k gal, IG plaster, Hayward 48sqft DE Filter, Hayward Max-Flo VS w/Pentair booster, Polaris 280 cleaner, installed 2003

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    Mod Squad tim5055's Avatar
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    Re: Mysterious pressure increase when changing between returns and waterfalls

    Quote Originally Posted by BCinAustin View Post
    Update from Hayward. They've confirmed that I've got the right ring, but admitted that my Northstar has a lot of power and can sometimes create enough pressure to budge the lid on start and shutoff. As a courtesy, they're going to send me a different ring that might create a tighter fit at the lid. I'll keep everyone posted. Thanks as always for the help.
    wow, that's customer service!
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Mysterious pressure increase when changing between returns and waterfalls

    This is awfully late, but I wanted to update folks in case they have the same issue. The new o-ring didn't help. Ultimately I had to buy an entire new lid with a preinstalled t-ring. That finally got me back to a good seal.
    16k gal, IG plaster, Hayward 48sqft DE Filter, Hayward Max-Flo VS w/Pentair booster, Polaris 280 cleaner, installed 2003

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    Mod Squad kimkats's Avatar
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    Re: Mysterious pressure increase when changing between returns and waterfalls

    Nice follow up! THANKS!

    kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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