Swapping motors with pump heads

[Ballvalve]

I have a few 1/2 hp 13 stage older - new Graingers submersible pumps. Probably Myers built, cast heads. The chart says 300' of head max with 20 psi output, about 2.3 GPM , by recollection. Having a few 1 and 1.5 HP Franklin motors laying about, what might I expect swapping them for the 1/2 hp motor?

The booklet from Graingers shows a 14 stage 1 hp maxing out around 375' . I am filling a water tank high up the hill, so I am not pressurizing anything. Do you full time pump masters stock pump heads and then add a motor to suit the site conditions?

 

[Valveman]

You can always add a larger HP motor to a smaller HP pump, never the other way around. But you will only get what the pump is rated for, the larger motor won't make it produce more water.

 

[Sponsor]

 

[Ballvalve]

You can always add a larger HP motor to a smaller HP pump, never the other way around. But you will only get what the pump is rated for, the larger motor won't make it produce more water.

So if I take a 13 stage pump with a factory mounted 1/2 hp motor, that makes 300' and about 2 psi, and add a 1.5 hp motor to it, I will still get the same ratings? Seems awfully counterintuitive, no? The same amount of water at 3x the amp draw? Are the impellers in a 13 stage 1/2 hp pump constructed differently from those in the factory built 1 hp, 13 stage rig?

 

[VAWellDriller]

yes

 

[Reach4]

Your motor is going to go a little short of 3600 RPM because of the way that 2-pole motors work on 60Hz. Even a motor with no load at all will run a little short of 3600 RPM./

I don't know about the impellers in the 13 stage pumps, but I would think they will be different. I would expect the pump designed for lower GPM would have shallower bite, and the higher GPM impellers would have a steeper byte. A little analogous to a fine pitch and course pitch screw thread.

 

[Valveman]

It is still a 1/2HP pump, still spinning at 3450 RPM, so it will still only pump 1/2HP water. It will not be pulling 3 times the amperage however. The larger motor will only cause an extra amp or two over the normal 1/2HP amperage.