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Thread: New pump, old plumbing

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    New pump, old plumbing

    Please bear with me . . . I'm posting this on behalf of my husband, so I may not get all the technical pool words right.

    It's time for us to replace our pool pump. We'd like to go for one of the new energy-efficient pumps, but most of them have 2-inch pipes. Our current plumbing is 1 1/2 inch pipes. Is it safe for the pump and the plumbing to go from 2 inches down to 1 1/2? We really don't want to have to replumb the whole pool! This is a standard-size inground pool (20 x 60). I can provide more info (c/o the hubby) if this isn't specific enough.

    Thanks in advance!

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    Mod Squad Bama Rambler's Avatar
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    Re: New pump, old plumbing

    It's perfectly safe to go from 1-1/2" to 2" piping. Tell us a little more about your pump and there are people here that can make recommendations.
    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
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    JasonLion's Avatar
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    Re: New pump, old plumbing

    Welcome to TFP!

    +1 what Bama Rambler said. Mixing pipe sizes is fine.
    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: New pump, old plumbing

    we have a hayward 1-1/2 hp superpump with 1-1/2 inch unions/pipes and want to upgrade to a energy efficient pump like the pentair whisperflo with 2 inch unions/pipes. We have about 40 feet of dynamic head and want a desired flow of about 60 gallons per minute. Based on the performance charts we would need a 1/2 hp or 3/4 hp pentair whisperflo pump but thats at 2 inch piping, What happens when I reduce the whisperflo from 2 inch unions/piping down to 1-1/2 inch piping ? We are going down in piping size, not up, so will the whisperflo maintain the same flow through 1-1/2 inch pipe as it does through 2 inch pipe? The pump speed is constant so the only restriction is the narrower pipe at 1-1/2 inch or maybe the narrower pipe doesn't make any difference at all. The performance might be the same either way! Will the whisperflo overheat and cavitate at the narrower pipe size - I don't know. Go out on the net and try to find the answer to this question and you will find there is no information forthcomming. Any ideas?

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    Re: New pump, old plumbing

    Just bumping this so maybe someone will see it and post a reply. We are anxious to get our pool opened for the season, and we need a new pump first! thx

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    In the Industry

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    Re: New pump, old plumbing

    We went exzactly the oppisite way last year
    we went from a whisper pump to a 1.5 hp pump. Hayward 1.5 pump is really the same as a 1 hp pump in performance compared to other brands. That is what I found out.
    Our flow increased signifigantly with the addition. We went with a true 1.5 hp pump
    I suspect that you may see a decrease in performance if you decrease in hp but I am no expert.
    Our biggest problem was that we have our auto cleaner on the same lines as well as solar panels.
    1.5 is just about right for us.

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    JasonLion's Avatar
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    Re: New pump, old plumbing

    With solar panels, or in-floor cleaners, or water features, or a spa, you often need a larger pump. But for a straight forward pool, you only need 3/4 HP full rated (1 HP up/max rated).

    1.5" plumbing isn't a major problem unless the pipe runs are relatively long. Using a pump with 2" connections on a pool with 1.5" plumbing isn't a problem. Using a larger HP pump on a pool with 1.5" plumbing can be a problem, but is usually just a waste of electricity.
    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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