getbit:
If it turns out
not to be the capacitor (which I would also check first) and you decide to get a new pump, multi-speed (a.k.a. variable-speed) pumps are the most energy efficient choice. Have to weigh the cost difference between 2-speed and multi-speed, though. Even with a 2-speed, you will see a significant energy use reduction compared to a single-speed pump. Your power cost would be a factor in this decision.
Many people assume that the relationship between pump speed and energy usage is linear. It is not. If you reduce the pump motor speed by half,
energy consumption will drop by significantly more than half. Even accounting for the fact that you have to run the pump for twice as long at half-speed in order to get an equivalent water turnover, the total energy consumption is still greatly reduced when running at half-speed for twice the amount of time vs. full-speed for half the time.
I hesitate to post specific energy reduction numbers since that opens the door to users posting different sets of numbers claiming theirs are right and everyone else’s are wrong. That risks denigrating the thread into a “my numbers vs. your numbers” debate even though all the numbers being batted around essentially tell the same story. However, the numbers debate would risk taking everyone’s eye off the ball of what’s really important to most pool owners in the market for a replacement pump:
Energy savings of 2-speed and multi-speed pumps are greater than many people realize. With all that said, I feel I owe you some guidance from a credible source on the magnitude of potential energy savings. So, as specific as I am going to get on this is by posting a reference to a page that succinctly describes the commonly-accepted relationship between pump speed and energy usage:
http://www.grundfos.com/service-support/encyclopedia-search/laws-of-affinity.html. The source is a worldwide manufacturer of pumps that makes approximately 16 million units annually. They probably know a thing or two about pumps.
Even if you add a fudge factor by doubling the power consumption numbers in the example quoted by the above source, you will see that there are still significant energy savings by replacing a single-speed pump with a 2-speed pump and even more savings by going with a multi-speed pump which provides even greater control of pump speed. That is what’s really important.
