Maximum GPM For 1.5" Pipe

[Chuck_Davis]

I just upgraded my Hayward SuperPump with a variable speed motor and 2.5 HP impeller. (See http://www.troublefreepool.com/thre...Motor-amp-Hayward-SuperPump-(aka-FrankenPump))

In Hayward's documentation for the SuperPump VS they recommend a maximum 45 GPM flow rate for 1.5" pipe.

My new pump has a button to speed the pump up to maximum RPM for vacuuming, but at max speed it is putting out 65-70 GPM.

Is the 45 GPM recommendation a "don't blow up your system" limit or am I safe to run at 65-70 GPM for vacuuming and backwashing? If 65-70 GPM is too high, is there a GPM flow rate between 45 and 65 that is safe?

 

[duraleigh]

You can run it as fast as you want. Not sure where they got 45 gpm but it there is no reason for it that I can think of.

Pool pumps commonly push 60-80 gpm through 1.5" pipe.

 

[JasonLion]

The particular filter wants 45-60 GPM when backwashing, and that range should also be just fine or even perhaps a little much when vacuuming.

There is no specific flow limit, but as the flow rate gets higher the system gets less efficient. 45 GPM is a suggestion of the max flow rate for reasonable efficiency, but that is just an arbitrary suggestion.

 

[chem geek]

See Maximum Flow Rates for PVC Pipes for more info. As Dave and Jason noted (posted around the time I was writing this), there really isn't a maximum, though it becomes very inefficient to use such narrow piping for higher flow rates since pump sizing and energy costs go up dramatically.