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Thread: Help on Motor Size (HP)

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    Help on Motor Size (HP)

    40 x 10 Pool with Spa , 8 jets in spa + 3 in pool. 2 motors 1 HP for pool circulation and 1 HP for 6 Waterfalls. 2nd motor is just for the water falls.
    Originally it had 1 HP Hayward for Pool and 1.5 HP Hayward for waterfalls. Started noticing weak waterfall from SPA , before motor burned out.
    They both burned out after 5 years. Replaced by my pool cleaning guy by 1 hp US motors (Emerson) for each side. The waterfall one keeps cycling ...gets really hot shuts off and then turns on like a 3 minutes cycling.
    I was curious and looked at original pool plans and it says it should of had 2 HP on each side. Is this correct? Did my pool builder under size my motors. Is this the reason they burned out so quickly?
    Even when my waterfalls had 1 1/2 motors it never shut down until it burnt out 5 years later.
    The 1 hp that was now put on waterfalls was already replaced thinking it was a defective new motor but keeps shutting off. A buddy of mine electrician check everything out for me and all connections are correct. He also checked the amps on both motors and its higher than whats on the label. Label says 6.8 and they are running at 10.6-11 amps.
    Please let me know if I should swap them out for 2hp motors on both sides.

    Thanks

  2. Back To Top    #2
    Mod Squad jblizzle's Avatar
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    Re: Help on Motor Size (HP)

    Welcome

    You may need to do some investigative work by looking at the impellers of the pumps.

    If they were indeed originally 2HP (what are the service factors as that can be a big difference), and the impellers are for a 2HP motor, putting a smaller motor on the large impeller would indeed over-work the motor and likely shorten their life. That could be why they are overheating.

    If the impeller is too large, you may be able to use a smaller one and then save electricity $ by using the smaller motors ... although hard to say how much life they may have left.
    Jason, TFP Moderator
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  3. Back To Top    #3

    Re: Help on Motor Size (HP)

    Im the original pool owner. The plans say 2 hp, but they never installed 2 HP They orignally installed 1HP on pool side and 1.5 on waterfalls. Now replaced by 1HP on each side. Shouldnt I replace both of these to 2hp motors?

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    Mod Squad Bama Rambler's Avatar
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    Re: Help on Motor Size (HP)

    Did you replace the whole pumps or just the motors?

    If it's just the motors then JB's advice is still accurate about replacing one with a smaller motor than the impeller needs.
    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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    Re: Help on Motor Size (HP)

    just replaced motors impeller is for 1 hp.

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    Mod Squad jblizzle's Avatar
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    Re: Help on Motor Size (HP)

    The motor should match the impeller ... I am still not 100% sure what motor / pump (impeller) combinations you are dealing with.

    Running a 1.5HP motor with a 1.5 impeller should not cause the motor to overheat ... even if the original spec was 2HP. You would just get a little less flow.

    Part of your confusion likely is due to the numbers game that the motor manufacturers play. You need to know the service factor of the motor as well as the HP and then multiply them together to get the SFHP. A 1.5 HP with a 1.33 SF is actually the same as a 2.0 HP with a 1.0 SF.
    Jason, TFP Moderator
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    Re: Help on Motor Size (HP)

    Both motors are 1HP and with 1 SF

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    Mod Squad Bama Rambler's Avatar
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    Re: Help on Motor Size (HP)

    Ok I'm confused.
    Originally it had 1 HP Hayward for Pool and 1.5 HP Hayward for waterfalls.
    They orignally installed 1HP on pool side and 1.5 on waterfalls. Now replaced by 1HP on each side.
    You said that you only replaced the motors with 1 hp motors but you also say that the pump for the waterfall was 1½ hp. Did you change the impeller on the 1½ hp pump with a 1 hp impeller?
    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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    Re: Help on Motor Size (HP)

    I just spoke to the guy the changed it and he left the 1.5 impeller on a 1 HP motor.
    He's going to change it tomorrow to a 1HP impeller to match motor of 1.0.
    Thanks

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    Mod Squad Bama Rambler's Avatar
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    Re: Help on Motor Size (HP)

    That will fix your problem.
    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
    Pool School ----- Pool Math ----- TF-Test Kit

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    Mod Squad jblizzle's Avatar
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    Re: Help on Motor Size (HP)

    That should help the motor.

    On a side note, 1HP seems a little small to me to be running a spa or 6 waterfalls. Do you have a blower for the spa? Still get enough flow out of the 6 waterfalls?
    Jason, TFP Moderator
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  12. Back To Top    #12

    Re: Help on Motor Size (HP)

    Thats what I thought since the pool plans indicated it to put 2 HP on each side. Pool Builder put 1 hp on pool side and 1 1/2 for waterfalls. They burned out. So my pool service guy replaced them with 1 HP on each side. I do have a 2 HP blower on SPA. I turn it on only when I use it. I originally though my motors burned out took quickly. 5 years? I thought this happened because not having enough power.

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    Mod Squad jblizzle's Avatar
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    Re: Help on Motor Size (HP)

    The motor/pumps combos will only move a certain amount of water based on the head loss in the plumbing. Having them too small will just reduce water flow, not make them work any harder.

    It is likely the motor/impeller mismatch is your current problem.

    As for why the motors only lasted 5 years ... that almost seems common with today's motors I think. We see people with 20yo motors running fine and then there are these that seem to die much earlier. If you keep an eye on the seals and fix leaks before the bearings are damaged you may be able to extend the life.
    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: Help on Motor Size (HP)

    Thanks, I'll let you know what happens.

  15. Back To Top    #15

    Re: Help on Motor Size (HP)

    Thanks for you help. Yesterday my pool guy installed the correct 1HP impeller to match 1 HP motor. Problem Solved no more overheating.

  16. Back To Top    #16
    Mod Squad jblizzle's Avatar
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    Re: Help on Motor Size (HP)

    Thanks for letting us know
    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
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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