Pump replacement for Northstar

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J

JerryInBAOK

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Mar 22, 2016
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Hello,

I have a question about replacement pump motors. I got about 8 or 9 years out of the original 1.5 hp motor for our Northstar pump. I finally had to replace it last April however I struggled with whose motor to buy.

I ended up buying a century and made the swap just fine (i also installed a new seal as well as impeller) . However, the new motor was never as quite as i expected it to be and i didnt feel as though it was creating the pressure i expected nor self priming as fast as i had been use to. Now the pump seems to be a little loader down another 5lbs and i think it may be going out.

I want to go ahead and replace it so i dont disturb the neighbors all night and was wondering who makes high quality motors these days? The only motors ive seen out there are Century and US Motors. How would you guys judge those two motors and is there a high quality option.

Thanks!
 
:wave: Welcome to TFP!!!

HP is only 1 part of understanding the power of a motor. You also need to look at the Service Factor (SF). To be the same power, the HP*SF must be the same. If the SF of your current motor is lower than your original, that would impact the longevity of your motor.

Beyond that, I would recommend going to a 2-speed version of your motor as they are MUCH quieter running on low that any pump running at full speed. Plus you save money on electricity.

One question though, based on your comment about disturbing the neighbors ... how long are you running your pump? Generally only a few hours are required for adequate circulation. Take a look at this article in Pool School: Determine Pump Run Time
 
Thanks Jason! I went out this morning and attempted to clear my impeller of debris. I didnt pull any out but the pump did get its 5lbs back and is a little less noisy. To answer question about pump hours i usually run it 6 to 8 hours per day. Im running it more now because im getting it ready and i usually run it 24/7 till its cleared which is normally about 4 to 5 days.

Im still curious about the motors. Ive read at various places on the net that i cant get as good as my original AO Smith and I just wanted to see what you guys thought about quality AO Smith alternatives
 
Most Hayward pump come with A.O.Smith motors and I think the are pretty well built. But there usually isn't much price difference with the alternatives so why bother. But you do have to be careful when choosing a motor for the Northstar because the SF is higher than a normal pump. So if you have a 1.5 HP full rated pump, you will want the B979 motor which is considered a 2 HP full rated motor.
 
mas985 said:
Most Hayward pump come with A.O.Smith motors and I think the are pretty well built. But there usually isn't much price difference with the alternatives so why bother. But you do have to be careful when choosing a motor for the Northstar because the SF is higher than a normal pump. So if you have a 1.5 HP full rated pump, you will want the B979 motor which is considered a 2 HP full rated motor.
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I don't understand your reply here. If the original motor is 1.5 full rated it's not a good idea to put a 2 full rated on. It would be a waste of money as it'd be more expensive than the 1.5 and you would only get the flow of the 1.5 via the impeller. If the OP could post the model number of the Northstar it'd help determining if the pump is full or max(up) rated. In my experience 95% of the Northstars I see are max rated and the replacement motor model number starts with USN. 1.5 hp would be USN1152 or full rated would be SN1152. Any other motor we've tried resulted in spun impellers. GL!
 
I replaced the original with a "Century Electric UST1152 1 1/2-Horsepower Up-Rated Round Flange Replacement Motor" of Amazon. Before purchase i found what i believe to have been accurate replacement cross references. I just went out and looked at it and it has a SF of 1.0 which i believe was the same as on the original NorthStar
 
Do you still have the model number sticker on the pump? It's located by the lid on the pump housing. UST motors are for Super II pumps, although you can use them on Northstars I've found the USN works better.

A little concerning is the 5psi reading, unless you have a 3" pipe to and from the pool I find that number to be low. Have you tried replacing the gauge on the filter to see if it's reading right? I can only imagine how loud the pump runs if the psi is truly 5.

One last thing to check, motors come pre-wired for 220v and some systems are 110v. Double check the incoming volts to be sure you have it wired right. Hard to believe if this is the case it's still running though.

GL!
 
JoelFitz said:
I don't understand your reply here. If the original motor is 1.5 full rated it's not a good idea to put a 2 full rated on. It would be a waste of money as it'd be more expensive than the 1.5 and you would only get the flow of the 1.5 via the impeller. If the OP could post the model number of the Northstar it'd help determining if the pump is full or max(up) rated. In my experience 95% of the Northstars I see are max rated and the replacement motor model number starts with USN. 1.5 hp would be USN1152 or full rated would be SN1152. Any other motor we've tried resulted in spun impellers. GL!
Click to expand...
Those are single speed motors and yes they would work fine. But I was suggesting the OP go with a two speed motor and when sizing a two speed motor or any motor for that matter, you need to always take into account the service factor because not every full rated 1 1/2 HP motor has a service factor of 1.6. And if the OP wants a two speed motor, and the pump is a full rated pump, then the correct motor is a B979 which has the SAME THP as the original motor (THP=2.4) but it is labeled as a 2 HP full rated motor. If you would go with the lower rated motor, a B977, which has a label HP of 1.5 and a service factor of only 1.3, this motor would be overloaded and would continuously shut down. Although the B977 is labeled as a full rated 1 1/2 HP motor, it would not work for a full rated 1 1/2 HP Northstar wet end. However, the B977 would work for an up rated 1 1/2 HP Northstar wet end.
 
JoelFitz said:
Do you still have the model number sticker on the pump? It's located by the lid on the pump housing. UST motors are for Super II pumps, although you can use them on Northstars I've found the USN works better.

A little concerning is the 5psi reading, unless you have a 3" pipe to and from the pool I find that number to be low. Have you tried replacing the gauge on the filter to see if it's reading right? I can only imagine how loud the pump runs if the psi is truly 5.

One last thing to check, motors come pre-wired for 220v and some systems are 110v. Double check the incoming volts to be sure you have it wired right. Hard to believe if this is the case it's still running though.

GL!
Click to expand...

Maybe i was a bit confusing. The motor had lost 5lbs, not running at 5. It was running at about 15 and know after i cleaned the impeller its back to running close to 20. Its wired correctly. I have made note that you are suggesting a USN which i will do next time around. Keep in mind i installed the current motor in april 2015, the original motor has been discarded. Couldnt find my Hayward manual but i know i have it around her somewhere.
 
Another way to size a pump properly is to get the part number of the impeller which is on the side of the impeller.
 

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