Power usage of two different HP Variable Speed Pumps at 1500 RPM

[ajw22]

my 2 speed 1 HP pump, say 2 or 3 HP will obviously cope better with the filter being clogged

A larger filter will cope better, not a larger pump.

You don’t have a signature telling us about your pool equipment but you probably have the typical too small Florida cartridge filter of 100 or 200 sq ft. A 400-500 sq ft filter will handle stuff a lot longer without affecting your flow.

 

[1poolman1]

Hi, based on my recent experiences trying to balance the HP of a pump with power consumed and GPM, I'd suggest you get a flow meter (Amazon around $80) to measure the actual flow as GPM is not directly proportional to RPM, impeller size and HP. Two factors, pipe diameter and the state of the filter directly affect the flow or GPM. Right now, we're getting yellow pollen dumped in the pool from trees that inside 2 days has reduced the low speed flow from 20 GPM to less than 5 GPM. This last for 1-2 weeks in March and we'll be back to normal after that. A more powerful pump than my 2 speed 1 HP pump, say 2 or 3 HP will obviously cope better with the filter being clogged but the power consumed increases exponentially to maintain an adequate flow even at a lower speed. Its all a trade off trying to balance size of pool, pump size, GPM, RPM and running costs whether its a VS pump or 2 speed pump. Single speed pumps should not even be considered.

Trying to use horsepower to force water through a very dirty (clogged) filter will be a waste of energy and can crush a cartridge, warp D.E. grids, cause channeling in a sand filter.

 

[Darin]

Hi, based on my recent experiences trying to balance the HP of a pump with power consumed and GPM, I'd suggest you get a flow meter (Amazon around $80) to measure the actual flow as GPM is not directly proportional to RPM, impeller size and HP. Two factors, pipe diameter and the state of the filter directly affect the flow or GPM. Right now, we're getting yellow pollen dumped in the pool from trees that inside 2 days has reduced the low speed flow from 20 GPM to less than 5 GPM. This last for 1-2 weeks in March and we'll be back to normal after that. A more powerful pump than my 2 speed 1 HP pump, say 2 or 3 HP will obviously cope better with the filter being clogged but the power consumed increases exponentially to maintain an adequate flow even at a lower speed. Its all a trade off trying to balance size of pool, pump size, GPM, RPM and running costs whether its a VS pump or 2 speed pump. Single speed pumps should not even be considered.

Flow is directly proportional to RPM i.e. half speed, half flow.

 

[Bill1974]

In a positive displacement pump, flow would be directly proportional to a RPM, but these are not positive displacement pumps, they are centrifugal pumps. The flow resistance the pump has to pump against is a factor in the flowrate. Pool pumps are low head pumps, so that flow resistance is a significant factor. Doubling RPM may get you 95%, 50% or 5% more flow, a lot depends on the pump design and what resistance it's pumping against. The closer to zero the flow resistance is, the more directly proportional the the rpm and flow are for a low head pump. On a low head pump the close you flow resistance is to the max pumping head the more non-linear the relation.

 

[1poolman1]

High flow vs High pressure pumps

In layman's terms, can someone explain to me what the difference is and in what application is each of these best used for?

www.troublefreepool.com

 

[Darin]

Pump affinity laws deal with like pressure, half flow half speed. There is no way using a pool pump where you can compare dynamic pressure. We just dont do that on this web site.