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Thread: pressure line conversion to suction

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    pressure line conversion to suction

    I have recently switched to suction side cleaner after my polaris was failing to often and never picked up dirt really well. The pressure line I know for sure is 1", when it comes down to using it as a suction line the general opinion is a "no" on these forums, but with the right pump speed and diversion with a 3 way valve the hydraulic flow should not be an issue other then the pump having extra pressure, so why is the answer always a no?

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    JasonLion's Avatar
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    Re: pressure line conversion to suction

    1" lines have a far higher resistance to water flow compared to 1 1/2" or 2" pipes. While you could in theory get a pump that would still be able to achieve the same flow rate despite the smaller pipe, no ordinary pool pump will be able to do that. Also the required suction levels are likely to damage the pipe, and create a personal hazard at the suction port. So, while it is not completely outside the range of possibility, especially if the run of small pipe is very short, it will almost never actually work out in practice.
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    Re: pressure line conversion to suction

    So your assuming the pressure inside the 1 inch line @ a 12ft run would be above bursting pressure?

    And with the extra suction since the vaccum would always be hooked up, I don't see the safety hazard.

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    Re: pressure line conversion to suction

    So since we would be adding more negative pressure to the 1 inch line what is the burst of typical pvc under negative pressure (vaccum) load?

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    Re: pressure line conversion to suction

    The head loss through the pipe will be very significant and could very well cause the pump to cavitate or at least lose prime because of the suction leaks. Pumps work ok with high head loss (small pipes) on the return side but do not on the suction side.

    But I would advise against going with a suction side cleaner unless you have only very fine dirt. Most suction sides don't do well with a lot of leaves. A few leaves, they work ok but if you have anything significant most cleaners will clog very quickly.

    The Polaris may not of had a decent bag on it that would filter out the dirt. With a fine bag, it should be able to do that.

    But if you are in the market for a new cleaner anyway, then I would look at ThePoolCleaner pressure side: www.thenpoolcleaner.com
    Mark
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    Re: pressure line conversion to suction

    12' is very short, there is some chance of it working if the total run is really that short, though likely not with any ordinary pool pump.

    It is going to be a suction line, so it isn't pressure, but vacuum that matters. The vacuum rating of most pipe doesn't leave nearly as much leeway as the pressure rating does.

    The hazard is from having hair or a finger held into the fitting due to the high suction. You would be unable to free yourself, and if a finger was caught, it would probably cut off circulation to your finger. If someone is around to turn off the pump then you will likely be fine, but if you are alone it could be a serious risk.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: pressure line conversion to suction

    I already own a kreppy and get very fine dirt, my pool has 1 main return line that's 1.5 and then it goes to 3 return jets where it must drop to 1 inch at the plaster, how hard is it to replace the pipe at the plaster to something larger to attach a flow direction fitting?

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    mas985's Avatar
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    Re: pressure line conversion to suction

    Not worth it in my opinion. Just run the cleaner off the skimmer.
    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: pressure line conversion to suction

    What about making my returns bigger because they are only 1 inch with no directional knob so I can't change the direction of flow in my pool

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    JasonLion's Avatar
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    Re: pressure line conversion to suction

    That shouldn't be all that difficult. Do you know what kind of connection, if any, they have? A typical return fitting is 1 1/2" female threaded. Yours might be anything from a bare pipe end to something more general. Once you figure out what it is it will be more obvious how to connect to it.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: pressure line conversion to suction

    So before the returns come out of the pool plaster I know the line is 1.5 and then it branches off to three returns at the pool plaster down to raw 1 inch pipe at pool plaster. So what should I do?

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    Re: pressure line conversion to suction

    Is it still bare 1" pipe on the water side of the plaster? Or is there a fitting of some kind?
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: pressure line conversion to suction

    Bare pvc no thread or fitting

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    JasonLion's Avatar
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    Re: pressure line conversion to suction

    The simplest thing to do is to use an inside slip coupling to connect to a short section of 1" pipe, a size changing bushing to expand that to 1 1/2", and connect to a slip to female threaded adapter, into which you can screw any standard return fitting. Several of the joints can overlap, but it will still stick out about 4".

    Another approach is to use a 1" 90 connected as close to the wall as possible, and then add any further adapters to that along the wall.

    The inside slip connector is the only part of that which is especially rare, they can be found, for example here.

    It is also possible, but far more work, to drill out the wall and install a standard 1 1/2" return fitting flush with the wall. However that will involve masonry drilling and plaster repair, which is a lot of work and will show (unless you completely re-plaster the pool).
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: pressure line conversion to suction


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    JasonLion's Avatar
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    Re: pressure line conversion to suction

    Look at that, exactly what you need.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: pressure line conversion to suction

    Product dimensions says omething else though so I'm skeptical

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    JasonLion's Avatar
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    Re: pressure line conversion to suction

    The Pentair catalog does appear to say that it is an inside slip fit for 1" pipe. There is a different part number for 1 1/2" pipe.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: pressure line conversion to suction

    Your so helpful, thanks Jason lion

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