Upgrading Pump Motor - New Impeller & Diffuser Too?

[TheMerk]

Should I upgrade the impeller and diffuser if upgrading my 1.0 HP pump‘s motor to a 1.65 HP VSP motor? If the answer is yes, I believe I need to go with a 1.5 HP impeller and diffuser, right?

My pump is a Sta-rite MPRA6E-147L. According to this manual, my impeller’s part no. is C105-236PB and the diffuser’s is C1-270PC.

INYO shows that both my impeller and diffuser are rated for 1 HP. Would the 1.5 HP impeller (C105-235PC) and diffuser (C1-270P) be the correct upgrade? Is there a worry that they won’t fit in my pump housing?

 

[ajw22]

@JamesW what do you think of his plan?

 

[JamesW]

The model numbers are ridiculously complicated. The horsepower is only the rated horsepower and not the total hp.

You have to know the total hp that the impeller needs.

Check with inyo about the right parts.

I would go with a new variable speed pump instead of rebuilding an old pump where the parts and labor are going to exceed the cost of the new pump.

 

[TheMerk]

I’m not concerned about labor. I’ve rebuilt other pumps before, and this looks fairly straightforward.

I chatted with Inyo. They say that my combination of new motor and existing filter should be ok with the existing impeller and diffuser.

Thst said, I had ordered the 1.5 HP impeller and diffuser. Would installing those impact things negatively?

 

[JamesW]

The pump model numbers and part numbers are confusing.

You can't go by the hp rating without knowing the service factor.

A "1 hp" motor might be 1 hp or 1.25 hp or 1.65 hp or 1.95 hp.

Going with 1.5 hp parts might be ok and maybe not depending on the original service factor.

 

[TheMerk]

The pump model numbers and part numbers are confusing.

You can't go by the hp rating without knowing the service factor.

A "1 hp" motor might be 1 hp or 1.25 hp or 1.65 hp or 1.95 hp.

Going with 1.5 hp parts might be ok and maybe not depending on the original service factor.

Current motor’s SF is 1.25:

 

[JamesW]

The problem is that you don't know the service factor of the pump that the 1.5 hp impeller goes to.

If the service factor is 1.1, you're good.

If it's higher than 1.1, you're going to overload the new 1.65 hp motor.

You can install the bigger impeller and then measure the current as the pump is running.

As long as the current doesn't exceed the label current (amps), you should be fine.

Just measure the current as you increase the rpm and keep the maximum rpm such that the amps are less than about 90% of the amps listed on the motor label.

 

[TheMerk]

Ah ok, that makes sense.

That manual I linked to above shows that the 1.5 HP pumps have the A100FLL motor.

Everything I can find about the A100FLL says that it has a 1.1 SF.

I think I may just stick with the original impeller and diffuser though, just in case. I’d rather not cause trouble down the line.