Pump impeller change


May 16, 2018
I just replaced my pump motor, 3/4" H.P. Century, 56Y frame, and I also ordered new seals and a new impeller. The OEM part # on the impeller is Pentair 073127 and that is what I ordered. When I went to install it, I noticed the new impeller is slightly larger than the old one. I went ahead and installed it since I wanted to get the pump going. Is this an issue or am I OK with a larger impeller ? I have noticed that my in-floor pop-ups are not working correctly, but that could be the control head. It has failed before and seems to have about a 3-4 year life span.

Thanks for any advice.


May 16, 2018
:wave: Welcome to TFP Bdarnell

Was it a 3/4 hp pump you replaced and was there a p/n on the old impeller ??
Well, what do you know. The old part # is 073126, not 073127 like the manual says. Good call.

Either the wrong impeller was installed at Pentair or the manual is wrong. Either way, the impeller I have on there now is what the chart in the manual calls out - 073127 for a 3/4 HP Whisper Flow pump.

Yes it was a 3/4 swap. Like for like.


LifeTime Supporter
TFP Guide
May 22, 2013
Hudson, WI
Hopefully that works out in your favor with the bigger impeller moving more water and or saving some electricity. Wrong impeller can cost you in efficiency and $$.


TFP Expert
Mar 2, 2011
You can't upsize the impeller. You will overheat the motor. It might work for a while, but the motor won't last long.

The 073126 impeller needs a total hp of 0.95.

The 073127 impeller needs a total hp of 1.25.

Total hp is rated hp x sf (label horsepower x service factor).

A 3/4 hp motor is ok for a 073127 impeller if the service factor is 1.67.

The 073126 Impeller goes to a WF-2,
WF-23 or a WFE-2.

The 073127 impeller goes to a WFE-3,
WFE-24, WF-3 or a WF-24.

The WF-23 is listed as a 3/4 hp pump with a 1.24 s.f for a total of 0.95 hp and takes a 073126 impeller. This is considered to be an up rated pump. This is probably what you have.

The WFE-3 is listed as a 3/4 hp pump with a 1.67 s.f for a total of 1.25 hp and takes a 073127 impeller. This is considered to be a full rated pump.

So, there are 2 different 3/4 hp pumps that are really not the same thing, which is confusing.

What is the pump model number?

What is the service factor for the new motor?