New Pool Pump Motor Overheating

[Chiz]

I installed a new motor due to the bearings going out on my old one. I have previously replaced the bearings on the old motor a couple of times before but this time it got real hot and melted the plastic fan and it would no longer fit on the shaft to spin and cool the motor. Long story short I neglected to do the proper research and purchased a smaller motor. The old motor was single speed 240V 1.5 HP / 1.5 SF (SFHP 2.25) and the new one is single speed 240V 1.5 HP / 1.1 SF (SFHP 1.65). It runs fine with normal pressure for a while but then the thermal protection kicks in and shuts if off. I now know (or think I know) I should get a smaller impeller to match my now smaller motor. I have a 1.5 HP pac fab challenger pump. Anybody familiar with these pumps know what impeller size I should be running with this new smaller motor?

Thanks,
Chiz

 

[Chiz]

Currently running the part # 35-5315 impeller which is a 1.5F, 2A... whatever that means. If the impeller measurements are calculated the same as motor SFHP measurements then it would seem this impeller is too big even for the old bigger motor that I had on there. So here's the next question, how are impeller measurements calculated? Am I assuming correctly that I multiply the impeller size of 1.5F, 2A to get 3? So my current impeller is almost double the size of what I need for my motor that has a SFHP of 1.65? If that is the case then it seems simple enough, but I'm probably assuming incorrectly and it is more complicated than that...

 

[scooperhsd]

I'm not sure on how to calculate on the impeller, but you definately put too small of a replacement motor if you just kept the existing impeller.

 

[mas985]

You just need to downsize by one impeller size (#355369 Impeller 1F, 1-1/2A). The F stands for full rated, the A up rated. You now have a 1.5 HP up rated motor. However, you can go with a smaller impeller if you want to. The flow rate will just be that much less but energy use goes down by a lot more.

 

[Chiz]

Thank you! I actually got that impeller this morning and got it installed and running just in time for this north Texas winter storm to hit. I appreciate the help.

Later,
Chiz