GPM of 1.5" vs 2" pipe??

Hi All,
Strange question. All of my plumbing is 1.5". I replumbed my new filter, pump etc using 2" pipe. I was able to do this since the Jandy valves accept 1.5" pipe either on the inside or 2" pipe on the outside of the valve.

The main drain and skimmer are limited in flow though because they both are 1.5" pipe going through a 1.5" Jandy valve (essentially a single 1.5" supply). Would it be worth it for me to replace that section to a 2" valve or does the 1.5" flow enough? I have a Pentair Whisperflo 3/4HP full rated pump and at 50ft head flows ~60gpm. My pressure gauge indicates ~13psi if that matters.

Thanks,
J.

Are your main drain and skimmer line separate, until you tee them together at the pump?

I have dual 1.5" suction lines (separate main drain and skimmer line) all the way to the pump. Dual 1.5" lines would give you plenty of flow, I have no problem feeding my .5HP northstar pump. I have the separate lines coming together at a 3 way Jandy valve........the suction lines go inside the inlets of the valve (1.5") and the feed to the pump I use 2" (mostly because the Northstar has 2" plumbing connections).

If the only section you can replace is near the equipment pad, its probably not worth it. If you have the 2 separate lines, it might be worth it just for operating sake to get a 3 way setup. I find it very useful because I can turn down suction to the main drain while vacuuming, and I can also use the main drain only when pumping the pool down for winterizing.

-Chris

Yes, my main drain and skimmer lines are separate 1.5" lines that link up through a 3 way Jandy valve (1.5") that is next to my equipment pad. Essentially mine is set up the same way as yours. Just wondering if it's worth it to go 2"? I now have 2 1.5" pipes with one 1.5" output.........seems wrong.

IMHO, a 3/4 hp pump is not affected much with the 1.5" PVC pipes. You will get better hydraulics with 2" pipes, but as Chris said, not enough to warrant replacing your 1.5" section from the Jandy valve to the pump inlet. Now if you were to replace all your PVC above ground to 2" plumbing, you will gain some flow and lower backpressure. This will be easier on your motor.

Two 1.5" lines are the equivalent of a single two inch line so in effect, you do have 2" lines going to the pool for the suction side.

Also, at 13 PSI, there doesn't seem to be much in the way of return head so you are ok.