I was thinking about getting a two/variable speed pump, to save energy costs, but then wondered how much I would save.
I saw some things on the net, including the pentair pool site, that claim considerable savings.
I started out trying to measure the current my pump was using (I borrowed a current probe from work), but the results I got did not make sense.
So, I measured at my electricity meter. There is a spinning thing on my meter, that makes one revolution per watt. I timed how many watts were used in about one minute, with the pump on and off. Did it three times
These are the worst (most expensive) set of results. Best case was $104 per year
0.238970588 watts/sec pump on
0.155979203 watts/sec pump off
0.082991385 delta (pump) watts/sec
2.390151901 kwatts for 8 hr day
2.987689877 kwatts for 10 hr day
0.255403587 $ per 8 hr day
0.319254484 $ per 10 hr day
116.5278866 annual cost for 10 hr days
This is for a 1.5 hp pump, that has a service factor of 1.5. I think the pump is larger than it needs to be, my pool was built with an infloor cleaning system, but it no longer works. I think the pump was sized for the cleaning system. I had started to look into it, and thought I could use a 3/4 or 1 hp pump.
But, based on these results, I can't justify changing my pump.
So, unless I messed up my calculations, a new pump is not in my future. I am surprised that the pump does not use more electricity than this. The 300 watts per hour it uses is less than 1/2 hp, since 1hp = 746 watts. So, I guess my 1.5 hp pump is not working that hard?
For the numbers above, I counted 13 watts in 54.5 seconds pump on, and 9 watts in 57.7 seconds pump off
I am lucky, my electricity cost is just under 11 cents per kwatt, so that helps.