How to read pump flow charts?

[manfacro]

Hi all, I am working on upgrading my pool pump. I have the charts for both what I have, vs what I’m thinking about.

(1hp version) https://hayward-pool-assets.com/assets/documents/pools/pdf/literature/MaxFlo_SS_2017_6.pdf

(1.5hpversion) https://www.circupool.com/assets/doc/CircuPool-SmartFlo-Variable-Speed-Pump-Manual.pdf

I translate the curves to be close to the same?

One thing of note, I have a solar heater so water gets pumped 25ft up.

Once the system/solar panels are primed and flowing, the rpms can be dropped? I guess there might be an issue if the return water from the panels falls down faster than the pump is pumping water up?

Thanks,

 

[mas985]

Forget the head curves. There is a much easier way to match flow rates with the old pump. Simply adjust RPM until the filter pressure reads the same value as it did with the old pump. However, you may be able to operate at a lower RPM than what matches your old pump. Single speed pumps generally are much more powerful than is what is required even for solar.

Once the system/solar panels are primed and flowing, the rpms can be dropped? I guess there might be an issue if the return water from the panels falls down faster than the pump is pumping water up?

Assuming you have a VRV at the top of the panels, the pump will need to maintain positive pressure at the VRV to keep it closed and prevent air from entering the system and coming out of the returns. This will determine the minimum RPM you can run at unless you lower the VRV elevation. The lower the VRV elevation, the lower the RPM that can be used but there are downsides. Typically, if you want maximum efficiency out of the panels, they should be operated at 0.1 GPM/sq-ft or higher. Second, lowering the VRV below the panel height and lowering the RPM will generally put the panels under a slight vacuum. This is ok if the panels are speced for vacuum operation which some are.

 

[manfacro]

Awesome, thanks for the info! I do have to ask, what is a VRV?

 

[mas985]

VRV is a vacuum release valve. It is typically installed in solar systems to enable self draining when the pump is shut off.