lnmnmns said:
We need to replace our pool pump motor (pump is Dura-Glas II, model # P4R6E-187L). Our current motor says it's 1hp, 115/230v, 1.65 SF, single speed, 3450 RPM
This is an full rated pump with a brake HP of 1.65. (SF x rated HP = brake HP)
...I have found AO Smith motors QC1102 (energy efficient full rated) & SQ1102 (standard full rated) & USQ1102 (standard uprated)...all are 1 hp but one is "uprated" and the other two aren't. What is the difference between the uprated and full rated and which should I get for a 1hp motor replacement?
The full rated ones.
Thank you very much for any help you can give me. I appreciate all I can get!
Pump manufacturers play a numbers game with pumps. They call it the service factor (SF). It's really a fudge factor.
The SF is multiplied by the pump HP to get the brake HP of the pump. By changing the SF and the rated HP they can make the SAME PUMP appear to be more powerful to the casual observer. Let me illustrate with an example from the Pentair Whisperflo line since they make both full rates and up rated pumps in this line.
A full rated 1 HP whisperflo will have a SF of 1.65 for a brake HP of 1.65 (SF x rated HP = brake HP so this is 1.65 SF x 1 HP pump = brake HP of 1.65
An up rated 1 1/2 HP whisperflo will have a SF of 1.1 and STILL has a brake HP of 1.65!!!!! (SF x rated HP = brake HP so this is 1.1 SF x 1.5 HP pump = brake HP of 1.65)
These two pumps are EXACTLY THE SAME EXCEPT FOR THE LABEL ON THEM! You can check the parts lists for them and find that they use exactly the same part numbers!!!!! Same impeller, volute, motor, etc.
Why do they do this? Well, there are a lot of rationalizations about how heavy the duty load is but in reality it's because people think bigger is better but with pumps this is often not true. Very few basic pools really need much more than a 3/4 or 1 hp full rated pump but sometimes that a hard sell to someone who doesn't understand the hydraulics of the plumbing.
Also, some pump lines are ONLY available in uprated so their pumps appear to be bigger for less money when compared to competitors pumps. Funny thing is sometimes the up rated pumps are a better deal pricewise compared to the equivalent full rated one and vice versa. Even though they are the same pump there is often quite a difference in the price! No explanation for that except marketing.
