Pump motor/impeller configuration help

[djfesta]

Dear Pool experts,
This is my first thread and I need help with the following:

I have a rectangular pool of 11,000 gallons and recently the motor of the pump went bad. The specifications of the motor are 1.5HP - SF: 1.1 - Total HP 1.65. Then I checked the impeller part number and I noticed it is a 0.75HP. That surprised very much and now I am confused what would be the right parts for my pool pump.
I will provide you all the parts numbers of the pool pump parts, if you can help me to determine what would be the right mix for the impeller and motor. I am looking for the more energy efficient alternative without over spending.

I was thinking that if I had an impeller of 3/4HP and a motor of 1.5HP- my logic says that switch to 1.1 total hp motor and 1hp impeller would do perfect fine and I would save money on my electric bill. I am wrong or right?

Motor Name Plate Info:
US MOTORS - CAT. NO. EUSQ1152 – MODEL C55CXKLT-5007 HP 1.5 SF 1.10 RPM 3450
Volts 230/115 HZ 60 - AMPS 8.5/17.0 - Frame 48Y

Housing Sta-Rite: Self Priming = MPRA6G-155L

Impeller C105-236P

Filter: Sta-Rite posi-flo II pool filter MODEL PTM135

thanks in advanced

Diego

 

[jblizzle]

Welcome to TFP!!!

The motor HP can be larger than the impeller HP without issue, but not the opposite.

In effect, your pump was operating at a 0.75 HP pump. If you put a 0.75 HP motor on it, the electrical consumption should basically be the same as your old motor.
If you put a 1HP impeller and 1HP motor on it, your flow rate and electrical usage will increase.

If you were happy with the flow rate of your old pump, I would suggest just getting a 0.75 or 1HP motor and putting it on the existing 0.75 HP impeller ... perhaps upgrading to a 2-speed version.

{Note, I did NOT verify that you do in fact have a 0.75HP impeller}

You could call up INYOpools and they would certainly help you match up a motor to your existing pump.

 

[djfesta]

Hi and thank you for the fast reply.

Very good explanation. I believe flow was good and powerful enough. I was able to vacuum with not problem. So keeping the same impeller and changing just the motor to 1hp I would be fine. Does the S.F. of the motor matter in this case?

 

[jblizzle]

You just need the Total HP or SFHP (service factor * HP) to be greater than required for the impeller.

So a 1HP 1SF would be plenty big or a 0.75HP 1.33SF or 0.75 HP 1.0 SF or even 0.5 HP 1.5 SF.

Again, suggest a 2-speed and run on low most of the time and then manually pick high speed for filter cleaning or vacuuming. Or you could add a timer to switch speeds also. Although I think most 2-speed are 230V, so be sure you have that available if you go that route.

 

[JamesW]

You have a StaRite DynaGlas pump. The original motor was 2.2 total hp. The original impeller was C105-236PDA and the original diffuser was a C1-270P.

The motor and impeller have been replaced. The new impeller (C105-236P) requires a motor with 1.0 total hp and uses diffuser C1-270PB.

The hp ratings are super complicated. They never are what they say.

For example, the full rated 1/2 hp pump has a service factor of 1.9 for a total of 0.95 hp.

The up-rated 3/4 hp pump has a service factor of 1.27 for a total hp of 0.95.

Both pumps are exactly the same in every way. The only difference is the label.

Both take a C105-236P impeller. So, if you look up the impeller, it might be listed as a 1/2 hp impeller or a 3/4 hp impeller but it takes a 0.95 hp motor. Very confusing for no reason.

The C105-236PDA impeller goes to a 1.5 hp full rated pump with a sf of 1.47 for a total of 2.2 hp.

The C105-236PDA impeller also goes to a 2 hp up rated pump with a sf of 1.1 for a total of 2.2 hp.

Again, the exact same pump except for the label. One is sold as a 1.5 hp pump and the other is sold as a 2 hp pump but both require a 2.2 total hp motor.

So, if you have a C105-236P impeller, you would need a motor with a total hp of 0.95. A 1.1 total hp would be fine.
The C105-236P impeller uses a C1-270PB diffuser.
You should also get a U9-373 Seal Plate Cord Ring, 17351-0101S Shaft Seal and U9-374 Diffuser O-Ring.

Alternate seal part numbers PS-201V-CMS or PS-1908.

Actually, the 0.95 and the 1.1 are probably the exact same motor. The manufacturer has a lot of slack in how they rate things.

The main reason for a 0.95 hp pump is regulations in states like California that require a single speed pump to be less than 1.0 hp.

If a filter pump is 1.0 hp or larger, it has to be two speed or variable speed.

You might want to just replace the whole pump with a variable speed pump. Pentair has a rebate available for the Superflo vs and local utilities often have rebates.

By the time you buy all the parts and rebuild the pump, it's usually better to just replace the pump.

The motor has already been replaced once. So, I suspect that the pump is pretty old. When you take it apart, you might find more parts that need to be replaced. The impeller and seal plate are not cheap.

At a minimum, I would recommend that you disassemble the pump to check the parts before buying a motor. If you need an impeller or seal plate, definitely replace the pump.

A variable speed pump is much quieter and much less expensive to run.

I would suggest a two speed pump with a maximum of 1.0 hp or a variable speed pump.

 

[jblizzle]

Awesome! Thanks James.!

 

[djfesta]

Thank you so much for your good explanation. I agree with you. probably the best action would be to buy a new pump with dual speed.

I found this one and I think it is very reasonable deal. What do you think about the model and specs.

Pentair 340042 SuperFlo High Performance Energy Efficient Two Speed Pool Pump, 1 Horsepower, 230 Volt, 1 Phase - Energy Star Certified


Amazon.com : Pentair 340042 SuperFlo High Performance Energy Efficient Two Speed Pool Pump, 1 Horsepower, 230 Volt, 1 Phase - Energy Star Certified : Swimming Pool Water Pumps : Garden Outdoor

Thank you again and if you any other recommendation, I will be very happy to hear.

 

[JamesW]

That should work assuming that the power supply is 230 volts.

Also, you need a switch to change speeds. I think that the pump comes with the switch on the back that you can use or you can use an external switch, such as a two speed timer or automation.

If you want the back mounted switch, check with the seller to make sure that the switch comes with the pump.

You should be able to run on low most of the time.