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Thread: Pump overheating: too much HP for pool?

  1. #1
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    Pump overheating: too much HP for pool?

    Hi all -- i just got a rebuilt 2 hp pump after the old one (1 hp) started buzzing. Seems to work OK at first but it gets very very hot after a few minutes of use. A few times it has auto shut down, and after a few minutes it would start back up.

    I've checked the breakers (I changed the one inside the house to a 30, since there's 10 wire running to the outside), made sure the connections to the motor are snug (they are clips), made sure the wires are not touching, the ground wire is firmly attached, the filters and everything is clean. The plumbing is 1.5, and the pool, which includes a spill-over spa all running on the same pump, is about 22k-25K gallons (it's 16'x36'). Pump-pool distance/elevation is average. And I made sure to change the impeller to that of a 2 hp.

    Could it be that I'm running too much HP power on the pool? What else could cause the pump to run hot? I just turned it on, and it ran for 30 minutes. But it was so hot as to water bubbled when I sprinkled the top of the motor case.
    10,000 Gallon Inground Fiberglass Pool
    Cartridge Filter
    Zodiac Duo Clear SWG
    3/4 HP Hayward Pump
    Taylor K-2006

  2. #2
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    Re: Pump overheating: too much HP for pool?

    Did you just replace the motor or the whole entire pump? You should NEVER use a more powerful motor on a less powerful pump assembly.
    1971 San Juan Fiberglass pool 12,000 gallons
    New Pentair Whisperflow 1hp
    New Pentair FNS DE filter 64sq
    All 1.5" piping and no heater
    1 skimmer, 1 main drain, and 2 returns

  3. #3
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    Re: Pump overheating: too much HP for pool?

    Quote Originally Posted by vln
    Did you just replace the motor or the whole entire pump? You should NEVER use a more powerful motor on a less powerful pump assembly.
    Kept the old pump (it's a Sta-rite Duraglas) but changed the empeller.
    10,000 Gallon Inground Fiberglass Pool
    Cartridge Filter
    Zodiac Duo Clear SWG
    3/4 HP Hayward Pump
    Taylor K-2006

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    Re: Pump overheating: too much HP for pool?

    That's why. Your using a much more powerful pump with an underpowered impeller.

    I'm surprised you haven't burned out the pump/seals for good. I would either A, replace the pump housing or B, return the new pump.

    Never mind I didn't read your changed the impeller. That's strange...
    1971 San Juan Fiberglass pool 12,000 gallons
    New Pentair Whisperflow 1hp
    New Pentair FNS DE filter 64sq
    All 1.5" piping and no heater
    1 skimmer, 1 main drain, and 2 returns

  5. #5
    Mod Squad Bama Rambler's Avatar
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    Re: Pump overheating: too much HP for pool?

    If you put a 2hp impeller on a 1hp motor it's no wonder it's running hot. You need to go back to a 1hp impeller designed to match that motor.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 1.5hp Dynamo pump. 24" Pentair Sand Dollar Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit
    You can stop SLAMing your pool when you pass the OCLT (You lose 1ppm or less FC overnight, & You have .5ppm CC's or less) & your water is clear.

  6. #6
    Mod Squad Melt In The Sun's Avatar
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    Re: Pump overheating: too much HP for pool?

    Seems like there's a bit of confusion...you have a 2 hp motor running a 2 hp impeller, right? A 2 hp motor with a 1 hp impeller will not cause problems. A 1 hp motor with a 2 hp impeller will.
    11,200 gal, Pebble-Tec; Tristar 2-speed 1hp - Swimclear 325 ft2 cart - SWG - A & A in-floor cleaner - Heat pump. For the poolside cooking, a Yoder Wichita and a Big Steel Keg!
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    Re: Pump overheating: too much HP for pool?

    Quote Originally Posted by Melt In The Sun
    Seems like there's a bit of confusion...you have a 2 hp motor running a 2 hp impeller, right? A 2 hp motor with a 1 hp impeller will not cause problems. A 1 hp motor with a 2 hp impeller will.
    Correct: I have a 2 hp motor running with a 2 hp impeller.

    The pump (a Sta-Rite Dyna-Glas/Dyna-Max -- not sure which one), as far as I can tell, is supposed to handle 2 hp. The diffuser, according to the part number (C1200PA) is good for up to 2.5 hp.
    10,000 Gallon Inground Fiberglass Pool
    Cartridge Filter
    Zodiac Duo Clear SWG
    3/4 HP Hayward Pump
    Taylor K-2006

  8. #8
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    Re: Pump overheating: too much HP for pool?

    You should try reading the voltage on the pump wires. Sounds like it may be overdrawing amps.
    1971 San Juan Fiberglass pool 12,000 gallons
    New Pentair Whisperflow 1hp
    New Pentair FNS DE filter 64sq
    All 1.5" piping and no heater
    1 skimmer, 1 main drain, and 2 returns

  9. #9
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    Re: Pump overheating: too much HP for pool?

    Quote Originally Posted by vln
    You should try reading the voltage on the pump wires. Sounds like it may be overdrawing amps.
    The max amps on the motor is 12.

    I'm running 12-gauge wire from the motor to the timer/timer to breaker, where I have 20 amps. From there I'm running 10 wire to the house breaker, where I have 30 amp breaker.
    10,000 Gallon Inground Fiberglass Pool
    Cartridge Filter
    Zodiac Duo Clear SWG
    3/4 HP Hayward Pump
    Taylor K-2006

  10. #10
    Senior Member mas985's Avatar
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    Re: Pump overheating: too much HP for pool?

    You may have a full rated 2 HP impeller on an uprated 2 HP motor which would also cause a problem. What is the service factor on the motor and the part# for the impeller?
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

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    Re: Pump overheating: too much HP for pool?

    Quote Originally Posted by mas985
    You may have a full rated 2 HP impeller on an uprated 2 HP motor which would also cause a problem. What is the service factor on the motor and the part# for the impeller?
    The SF, according to the label (the motor, an A.O. Smith, was rebuilt; not sure if to original specs) is 1.1.

    Will have to take apart the pump tomorrow to see. I do remember the guy who sold me the motor installed another one, and I saw that the water channel (for lack of better term) was about 75 percent wider than the old one for 1 hp.
    10,000 Gallon Inground Fiberglass Pool
    Cartridge Filter
    Zodiac Duo Clear SWG
    3/4 HP Hayward Pump
    Taylor K-2006

  12. #12
    Senior Member 4JawChuck's Avatar
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    Re: Pump overheating: too much HP for pool?

    Your "rebuilt" 2 HP motor likely has a shorted armature, thats why its overheating. Probably why it was discarded for a new one in the first place. You can check the armature for shorts using an armature "growler"...but I would just get my money back and get a new 1HP motor instead of some "rebuilt" one from this guy.
    55 Kilolitre in-ground 18'X36' vinyl lined kidney shape, 1HP pump, Jacuzzi 250lb sand filter, RayPak Delta T 200K BTU natural gas heater. New PoolWerks "Blue Diffusion" liner on May 26th-2011
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  13. #13
    Senior Member mas985's Avatar
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    Re: Pump overheating: too much HP for pool?

    Quote Originally Posted by op999
    The SF, according to the label (the motor, an A.O. Smith, was rebuilt; not sure if to original specs) is 1.1.

    Will have to take apart the pump tomorrow to see. I do remember the guy who sold me the motor installed another one, and I saw that the water channel (for lack of better term) was about 75 percent wider than the old one for 1 hp.
    A SF of 1.1 is an uprated motor so you should be using a full rated 1.5 HP impeller. But if the impeller is sized for a full rated 2 HP motor, then it will likely cause the motor to overheat.

    If the impeller is sized correctly then it probably is the motor itself and should be the installer who replace it. Is there a reason you upsized the pump in the process?
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

  14. #14
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    Re: Pump overheating: too much HP for pool?

    Quote Originally Posted by mas985
    Quote Originally Posted by op999
    The SF, according to the label (the motor, an A.O. Smith, was rebuilt; not sure if to original specs) is 1.1.

    Will have to take apart the pump tomorrow to see. I do remember the guy who sold me the motor installed another one, and I saw that the water channel (for lack of better term) was about 75 percent wider than the old one for 1 hp.
    A SF of 1.1 is an uprated motor so you should be using a full rated 1.5 HP impeller. But if the impeller is sized for a full rated 2 HP motor, then it will likely cause the motor to overheat.

    If the impeller is sized correctly then it probably is the motor itself and should be the installer who replace it. Is there a reason you upsized the pump in the process?

    I believe the impeller is for a 2, so that may be it.

    But, giving it more consideration, I may go back to a 1.5 motor. (The man who I bought the pump from has 1.5 as well). I bought the 2 thinking that, since it's a larger pool with a spill-over spa, it would work better. He said he'd work with me and we can trade down.

    But now I am stuck with a 2 hp impeller. Will that works for a 1.5 hp motor?
    10,000 Gallon Inground Fiberglass Pool
    Cartridge Filter
    Zodiac Duo Clear SWG
    3/4 HP Hayward Pump
    Taylor K-2006

  15. #15
    Mod Squad Bama Rambler's Avatar
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    Re: Pump overheating: too much HP for pool?

    Quote Originally Posted by op999
    But now I am stuck with a 2 hp impeller. Will that works for a 1.5 hp motor?
    No, Your problem now is that your impeller is too much for your motor. If you go to a 1½hp motor you'll have to know the SFHP (service factor horse power) in order to get the correct impeller to match it.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 1.5hp Dynamo pump. 24" Pentair Sand Dollar Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit
    You can stop SLAMing your pool when you pass the OCLT (You lose 1ppm or less FC overnight, & You have .5ppm CC's or less) & your water is clear.

  16. #16
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    Re: Pump overheating: too much HP for pool?

    Quote Originally Posted by Bama Rambler
    Quote Originally Posted by op999
    But now I am stuck with a 2 hp impeller. Will that works for a 1.5 hp motor?
    No, Your problem now is that your impeller is too much for your motor. If you go to a 1½hp motor you'll have to know the SFHP (service factor horse power) in order to get the correct impeller to match it.
    Well what's a good range so I can figure out what impeller I will need?

    (He has a variety of motors; last time he just gave me one, but I think he'll let me me pick my own, now that the impeller has come into play.)
    10,000 Gallon Inground Fiberglass Pool
    Cartridge Filter
    Zodiac Duo Clear SWG
    3/4 HP Hayward Pump
    Taylor K-2006

  17. #17
    Senior Member mas985's Avatar
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    Re: Pump overheating: too much HP for pool?

    You really don't need much HP for your size pool. I have a 1/2 HP pump for a 20k pool so unless you need a lot of flow rate for something else, spa jets or water features, I would downsize both the impeller and motor. Just make sure they are a matched set. Do you still have the 1 HP impeller or is that from a different pump all together?
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

  18. #18
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    Re: Pump overheating: too much HP for pool?

    Quote Originally Posted by mas985
    You really don't need much HP for your size pool. I have a 1/2 HP pump for a 20k pool so unless you need a lot of flow rate for something else, spa jets or water features, I would downsize both the impeller and motor. Just make sure they are a matched set. Do you still have the 1 HP impeller or is that from a different pump all together?
    Well I was thinking that, since the average starting pool is about 15K, and mine's 25K (with a spillover spa), it would work. With 1 HP, the spa didn't push out much water.

    At first I was thinking a 2 HP would work fine, but I'm starting to see otherwise.

    As for the impeller, the old 1 HP one was shot (overheated a few times perhaps and was damaged), so I bought a second-hand one for a 2 HP.
    10,000 Gallon Inground Fiberglass Pool
    Cartridge Filter
    Zodiac Duo Clear SWG
    3/4 HP Hayward Pump
    Taylor K-2006

  19. #19
    Senior Member mas985's Avatar
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    Re: Pump overheating: too much HP for pool?

    Are you using the same pump for the spa jets? If so, then a two speed 2 HP might be the solution. You have high speed for the jets and low speed for the pool.

    If you have a separate pump for the jets, then the pool pump is just needed for circulation. If you want a dramatic spa overflow, then you might need more flow rate but that will be at the expense of energy consumption. Plus you really don't get that much more flow rate (~20%) out of a 2 HP than a 1 HP but the energy consumption is a lot more.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

  20. #20
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    Re: Pump overheating: too much HP for pool?

    Quote Originally Posted by mas985
    Are you using the same pump for the spa jets? If so, then a two speed 2 HP might be the solution. You have high speed for the jets and low speed for the pool.

    If you have a separate pump for the jets, then the pool pump is just needed for circulation. If you want a dramatic spa overflow, then you might need more flow rate but that will be at the expense of energy consumption. Plus you really don't get that much more flow rate (~20%) out of a 2 HP than a 1 HP but the energy consumption is a lot more.
    Yes I am running the same pump for both.

    However, I've never been a fan of that spa. It doesn't have a heater, and even if it did, it's harder (and more costly) to keep warm than an external/normal hot tub. Not that I use it much (if ever), but it seems to get dirtier more than the pool. So my guess was a higher HP motor to circulate water better.

    I think I am now deciding on whether to go to 1.5, or just go back to a 1 hp. Does a 1 vs. 1.5 make a big difference?
    10,000 Gallon Inground Fiberglass Pool
    Cartridge Filter
    Zodiac Duo Clear SWG
    3/4 HP Hayward Pump
    Taylor K-2006

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