Pump Replacement - Help

[garyduse]

I'm considering replacing both my main circulation pump (1 hp Sta-Rite DuraGlas) and booster pump (3/4 hp, A.O. Smith motor, driving a Polaris 380). Flowmeter on return line shows a flowrate of 53 gpm. From measurements made a couple years ago, I had a pump suction pressure of -15" Hg and a discharge pressure (filter inlet) of 11 psig, for a Total Dynamic Head of 42.4 ft. I have no attached spa, water features. Just two 1-1/2" return lines and a return to drive the Polaris.

I believe the original circ pump was just a 3/4 hp and, for reasons long since forgotten, I replaced it with the larger 1 hp pump. Probably in response to the Pool Store's "bigger is better" mantra. The 3/4 hp booster pump is the original (rebuilt a couple times) seems like overkill as I need to add a return line flow restriction (pinched valve downstream from pump discharge) to keep from overdriving the Polaris.

So, I'm wondering if my pocketbook would benefit from smaller pumps (run longer, if necessary) in one, or both, cases. I've looked at the guide in poolplaza.com, but they don't provide info for the smaller size pumps. Would I benefit from a 2-speed or variable speed motor?

Any pump recommendations (or websites for sizing info) would be appreciated.

 

[JasonLion]

A standard pump won't drive a Polaris 380. It really requires the higher pressure from a booster pump. There are some parts you can replace to turn it into a 360, which will work with a regular pump.

As a general rule, getting a smaller pump, or a two speed pump run on low, can save you a significant amount of electricity. In your case, with a fairly large pool, getting a two speed pump makes the most sense, since you might need high speed every now and then.