Multi Speed/Two Speed Swimming Pool PumpsFor SCE customers: Get $350 back when you purchase a qualified variable-speed pool pump between September 3, 2010 and December 31, 2010, and install it by February 28, 2011.
So how do multi speed pumps save electricity and how do they work? Well lets say your swimming pool pump is an energy efficient pump, and your pool is 20,000 gallons. We will base this comparison on electricity cost of 15 cents per kilowatt hour. A) If you have a 1 horsepower pump, you must run pump 5.3 hours to turn over(run 20,000 gallons through filter once a day) . That comes to $458.00 a year. B) A multi speed permanent magnet motor could turn over the same volume of water in 10 hours for a cost of $115.00 a year, PLUS have up to 3 horsepower available for things such as spa jet power! Now these comparisons are general: your pump may NOT be energy efficient or in good working order and your electrical costs could be more(making your savings higher), but if you combine the energy savings along with rebates you may get from your electrical company,its easy to see these pumps will pay for themselves!...also,the energy savings stated above are very conservative! Pump Affinity LawSpeed R.P.M.(revolutions per minute) = Flow G.P.M (gallons per minute) Speed R.P.M. = Power3 (energy used) Example: Reduce speed3000 RPM --> 1500 RPM1/2 Speed RPM = 1/2 GPM 1/2 Speed RPM = 1/2 x 1/2 x 1/2 = 1/8 energy used 3000 RPM -> 1000 RPM1/3 Speed RPM = 1/3 GPM 1/3 Speed RPM = 1/3 x 1/3 x 1/3= 1/27 energy used On the last example above,you can see how you must run pump 3 times longer because you are pumping only 1/3 the gallons per minute....however,you are only using 1/27 the energy so even if you run pump three times as long,you are only using 1/9 the energy and thats where the savings are! Multi speed pumps offer several advantages over single speed pumps 1)Much quieter(can be run at night when temperatures are cooler,leading to longer motor life) 2)In some areas electricity is less expensive at night especially in summer 3)Water filters better at low speed,resulting in smaller particles being filtered out(especially noticeable at night with pool light) However,there are some circumstances where low speed cannot be used: 1)If your swimming pool equipment is much higher than pool level (unless you have a "programmable" system where the pump can come on at high speed for a few minutes to catch prime and then switch to low speed. 2)If you have solar panels which create more resistance to flow (again if you have programmable system with valve that closes when solar panels are not being used then the pump can be switched to a lower speed at these times.) 3)If you have a suction type automatic pool cleaner,it may not work on low speed. It depends on the type of cleaner and the HP of pump. For example,I have found that Kreepy Krauly pool cleaners work great on low speed,however some cleaners like Pool Vac or Navigator may work on a 2 HP low speed pump but not a 1.5 HP low speed pump. If you have a dedicated line for a pool cleaner and automatic controls,the pool cleaner can be programmed to come on high speed for an hour, and then the valve turned by actuator to skimmer and motor switched to low speed for rest of night. Also, multi speed pumps generally have a 3 H.P. impeller, unlike most two speed pumps, so the impeller pulls more water even at lower speeds.
Below are two types of multi speed pumps
Below are the keypads for pumps 
Click the pump below to check price from an affiliate vendor:
Multi-speed pumps work in the same way as two speed pumps,but can be run at any RPM(revolutions per minute). This means they can be run at even lower speeds than 2 speed pumps. (A two speed pump runs at about 1725 RPM's at low speed)...I have installed multi speed pumps that filter the water fine(AND also run an automatic pool vacuum) at 1400 or 1500 RPM....Multi speed pumps have several advantages over two speed pumps,and there are several companies that make or are in the process of releasing multi speed pumps this year(2008) but here are a few advantages of some of the models out now (not ALL multi speed pumps have ALL these features): 1)Can save more electricity than 2 speed pumps(depending on speed selected and 2 speed pump's HP). With multi speed pumps you get a lower low setting and a higher high setting. A two speed pump has a set horsepower at high speed,and low speed is half the RPM's...so with a multi speed pump you can use less electricity than a two speed pump on day to day filtering, but get higher flow than a two speed pump for something like a waterfall or spa jets. 2)Have built in software that shuts pump off if it runs dry saving costly repairs 3)Built with permanent magnet motors that produce less heat than regular induction motors,and also 30% more efficient 4)Has software that automatically finds the most efficient speed to run(RPM's) 5)If you have automatic controls,you set a different speed for different functions(low speed for filtering,high speed for spa jets,medium for a waterfall or other water feature,etc. 6) Rebates that now apply for 2 speed/multi speed pumps may only apply to multi speed pumps in near future 7)Also available with software that shuts off pump in case of cavitation (such as a child getting stuck on main drain) Disadvantages: 1)More expensive than two speed pumps 2)If you are in an area where you are only paying 10 cents a kilowatt hour,it may not be worth it to buy a multi speed pump (instead of a 2 speed pump) unless:
A):You have a waterfall,fountain,spa,or the equipment is raised above the level of pool or some other reason you may need a higher horsepower or more rpm's than a two speed pump B):You have a very large pool which requires more time to turn over water C):You simply want the MOST energy savings and the best equipment. The link below will take you to a pool pump energy cost calculator that will give you a basic idea of energy savings with one of these type of pumps:
multi speed pool pump energy calculator
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