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Thread: How can you tell when a pump is bad?

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    How can you tell when a pump is bad?

    I ordered a new gage (and they seem to be a very high quality gage for the same or less than the cheap china gages) when I ordered my testing chemical refills and installed it tonight. On the new gage I am only getting 11.5psi. My pool has the skimmer and main return that a piped 2 into 1 with a jandy valve at the pump. I have 3 returns and when we bought the house last year only 2 were used with the extra ready for a heater. We installed a heater and with 3 returns there is not enough pressure to get water to the top of the slide so I plugged one off. I plugged one of the returns off and have enough to use the slide but it seems like I could use more pressure. I just cleaned the skimmer basket, pump basket, and backflushed the filter, it seems like this is as good as it gets. Am I due for a new pump? The motor was new last year but is a single speed motor, would I be better with a multi speed motor that I can turn up when we are going to use the slide? Thanks
    21,000 gallon IG with vinyl liner, Pentair sand filter, TF100 test kit, pool is about 15 years old.
    new in 2016 - Hayward SWCG with T15 cell

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    BoDarville's Avatar
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    Re: How can you tell when a pump is bad?

    One thing's not clear from your post...Was the lack of pressure to get water to the top of the slide something that was occurring before you got the new gauge?

    If you are getting a different reading on the new gauge vs. the old one, I would be more inclined to trust the new gauge.

    When someone talks of a pump going bad, it is usually the motor as opposed to the pump itself, which we sometimes refer to as the "wet end". Usually what happens is the motor becomes louder and begins sounding like what some have described as marbles in a tin can. Usually that's a sign that the motor bearings are failing. As for the pump (wet-end) itself, it is possible that the impeller may have sustained some damage or has worn down enough to noticeably reduce flow, although this is a bit rare and would take an unusual amount of debris passing through the pump filter basket over a long period of time for this to happen.

    It also could be that the current pump is fine, but is now insufficient to generate the pressure needed with the extra return, heater, and slide. If your current pump checks out fine, but it is determined that it does not have the power to generate the water flow you need with your current plumbing setup, I would replace the current pump/motor with a new packaged unit (pump & motor). You would definitely be better off with a 2-speed or variable-speed motor. While it's possible to replace just the motor on an existing pump, you would normally replace the motor with one of equivalent Service Factor HP as the motor and pump impeller must be matched in order to function properly. However, if more pumping power is needed when using the slide and all 3 returns, then simply replacing the current motor with an equivalent new one will not solve your problem. Therefore, a new pump/motor unit is what you would need. It may be worth the cost of a consulting fee to get a trusted expert out there to determine the size and power of the pump/motor that should be installed for your specific pool. You want a pump/motor that has the power you need and no more. The multi-speed motor will give you the flexibility to ramp it up when you need it and dial it down for basic water circulation when the slide is not in use.
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    Re: How can you tell when a pump is bad?

    Thanks for the reply. This is actually the 3rd gage I have had and this one is the best. First gage was a 0-100 gage so I bought a 0-30 and this spring the 0-30 wouldn't go back to 0. The current pump is an ITT Marlow that came with the pool and I am guessing that this was sized for the pool correctly, what I am unsure of is if the new motor is the correct one. The motor is the same hp (1 hp motor) but I do not know if it is the same operating RPM. Can you get different rpm motors that would then turn the pump faster and give me more pressure? I would like to be able to have all 3 returns going and to use the slide, that's where I thought a 2 speed motor would work, kick it into high when using the slide. I had some issues with this last year when the filter would get dirty, about the same as this year but now I am trying to run 3 returns.
    21,000 gallon IG with vinyl liner, Pentair sand filter, TF100 test kit, pool is about 15 years old.
    new in 2016 - Hayward SWCG with T15 cell

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    Mod Squad zea3's Avatar
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    Re: How can you tell when a pump is bad?

    In order to see if you have the same size motor you need to compare the service factor as well as the horsepower. If you have the old motor look on the label for the SF and look at the SF on the new motor. Post the SF here.
    TFP Moderator
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    Vogue 21' round AG, Pentair 1 hp 2 speed pump, 36 sq ft DE filter, Hayward S180T 150# sand filter, Houston, Texas
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    Re: How can you tell when a pump is bad?

    I don't have the old motor, the current motor runs at 3450 rpm so I am guessing this is the most I will be able to get out of this pump. I am also guessing it is running at the pressure it should, when I looked in the manual it used as an example of when to flush the filter and used a starting psi of 11, which is what I am running at. What psi do others with a similar setup usually run (IG with a slide)?
    21,000 gallon IG with vinyl liner, Pentair sand filter, TF100 test kit, pool is about 15 years old.
    new in 2016 - Hayward SWCG with T15 cell

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