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Thread: Pump motor temperature

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    Pump motor temperature

    Hello,
    I have a Hayward northstar pump that is about 10 years old. I bought this house last year and the prior owner apparently replaced the original Hayward motor with an after market motor. The motor running temperature is a constant 200 degrees F at the case. Also The pump is not in direct sunlight and there does not appear to be any air flow restrictions.

    This seems quite hot to me, but I have none to compare it too; it has always run at this temperature since I have owned it. Can someone please confirm if this is normal.

    The pump assembly runs loud too; not like screaming bearings, just loud like a small humming diesel engine.

    I wonder if the previous owner installed an undersized motor on that pump and it is working too hard...is this possible? The previous owner left the the original Hayward motor (2hp) in the garage, but it is wasted.

    I am a new pool owner and appreciate this forum....thanks,

    Jeff in Florida

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    duraleigh's Avatar
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    Re: Pump motor temperature

    Welcome to the forum.
    an undersized motor on that pump and it is working too hard...is this possible?
    No. A constant speed pump doesn't work like that.

    Pump motors run notoriously hot....almost always too hot to touch. However, I'm not sure about one that runs 200. Unless the noise is bothering you, let it run it's course. If the noise is troublesome, replace it but bear in mind that many of them (mine included) are a bit noisy. A 2-speed on low would make a huge difference volume-wise.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Pump motor temperature

    It seems a pump impeller sized for 2hp motor, but driven by a 1.5hp would overload the motor, since both attempt to run at the same RPM.
    Is it not possible to incorrectly mate these mismatch components?

    Since the pool has a cascading spa water fall, a variable speed pump is not an option.

    Jeff in Florida

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    Mod Squad jblizzle's Avatar
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    Re: Pump motor temperature

    Quote Originally Posted by uman
    It seems a pump impeller sized for 2hp motor, but driven by a 1.5hp would overload the motor, since both attempt to run at the same RPM.
    Is it not possible to incorrectly mate these mismatch components?

    Since the pool has a cascading spa water fall, a variable speed pump is not an option.
    I am pretty sure you are right. Putting a motor that is smaller than the impeller will over work the motor and likely cause extra heat (at least that is what I thought I learned from Mark (mas985)). I think Dave may have misread your question.

    What does the cascading water fall have to do with not having a 2-speed or variable speed pump? Just means it would cascade a little less .......
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Pump motor temperature

    Without the proper water inflow volume into the spa, it would just dribble over the spillway into the pool. I suspect a stain would follow after many moons.

    But 200 degrees....really?

    Jeff in Florida

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    Mod Squad jblizzle's Avatar
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    Re: Pump motor temperature

    I had a motor start to go bad and I could smell it, starts to discolor the labels and eventually started to trip its thermal protection switch. Dripping water onto it would sizzle ... so must have been over 212 degrees.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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    mas985's Avatar
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    Re: Pump motor temperature

    Most residential pool pump motors have insulation ratings of Class B which is good to 130C or 266 F so 200 F is getting close and is probably at the high end of what is normal.

    The pump assembly runs loud too; not like screaming bearings, just loud like a small humming diesel engine.
    This usually means the bearings are failing which also causes extra load on the motor and raises the operating temperature. This is likely the cause of the excess heat.
    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: Pump motor temperature

    High motor temperature problem solved.....
    The previous owner replaced the original Hayward pump motor with a non-OEM motor and this motor was running at a temperature of 200f.
    The original motor was a Hayward 2hp and 1.35 service factor (SF) which = 2.7hp
    The replacement non-OEM motor was a 2hp and 1.0 SF which = 2.0hp.
    Both motors were running the Hayward impeller for for rated pump.

    Apparently the impeller load was greater than the design capability of the motor and I suspect the motor could not produce the rated RPM. The motor current increases and heat is the byproduct.

    Of course the cat hair in the motor intake did not help the condition either. The Hayward pump does make it difficult to inspect this area. I think in the future I will annually check/clean the motor vents.

    A new Hayward OEM motor + impeller was installed; this increased the pump GPM, reduced the noise level and reduced the operating temperature of the motor case to 115f.

    The pump motor is now purring along, but I can still hear it from the pool area....this will be the next pursuit.

    -Jeff in Florida

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