Measuring pressure with VS pumps

[Rollercoastr]

This issue came to mind when I started recording pressure in the Pool Math app.

Do most people with VS pumps measure pressure only at full-speed? I (almost) never run my pump at full 3,450 RPM, so I decided to log my pressure at 3,000 RPM instead.

 

[pooldv]

Yes, people with VS pumps need to check filter pressure at a higher rpm. I use 2500 because that is what speed 4 is set to on my pump. 3000 is fine as long as you remember to use 3000 next time.

 

[Rollercoastr]

Makes sense. So a suggestion for Pool Math App is to edit the pressure so it can be entered as PSI @ RPM...

 

[AftonJeeper]

Yes, people with VS pumps need to check filter pressure at a higher rpm. I use 2500 because that is what speed 4 is set to on my pump. 3000 is fine as long as you remember to use 3000 next time.

Out of curiosity why at the higher RPM? My pump is set to run at 1200 for filtering, higher for heating, and even higher for our water feature. I know it is just below 10 PSI at 1200 and I know, because of this site, to look for a 25% increase in PSI.

 

[pooldv]

The 25% increase is based on old, single speed pumps which only run at 3450 rpm or 2 speed pumps running on high speed which is also 3450. I doubt you'll ever see a 25% pressure increase at low rpm.

 

[AftonJeeper]

The 25% increase is based on old, single speed pumps

Then why is it referenced in the filter maintenance and cleaning section of pool school?

 

[pooldv]

What? Because that is when the filter should be cleaned, after the pressure rises 20-25% above clean pressure at high speed on a pump. I guess i don't understand your question.

 

[AftonJeeper]

I was curious why I should know my PSI at the higher RPM. I don't know if the pressure rise is a constant and will the be same percentage at any given RPM. Or if because I am running at a low RPM I may never see a PSI increase.

 

[slickraft]

What? Because that is when the filter should be cleaned, after the pressure rises 20-25% above clean pressure at high speed on a pump. I guess i don't understand your question.

AftonJeeper is simply pointing out that the reference to filter pressure rising 25% in that Pool School topic makes no consideration for the lower speeds of VSP's. I think most people here understand that 25% would be when observed at the highest pump speed but if you are new here, it might not be that intuitive.

 

[AftonJeeper]

AftonJeeper is simply pointing out that the reference to filter pressure rising 25% in that Pool School topic makes no consideration for the lower speeds of VSP's. I think most people here understand that 25% would be when observed at the highest pump speed but if you are new here, it might not be that intuitive.

I saw no reference to the highest pump speed in what I read. Thank you.