Energy-Efficiency

Single speed pump. Cheap to install. Costly to operate as electricity costs increase.  Consider a very common example:  A pool and spa combination shares a single speed 2hp Wisperflow pump.  Installed, this pump is about $1049.  If a home owner runs this pump 6 hours a day for a year, they will pay about $1200 per year in electricity.  Thus, the first year cost for the cheap way is $1049 (installation) + $1200 (usage) for a total of $2249.

Multi speed pump: A premium to install, but economical to operate.  If the home owner in the above example had chosen a 1 1/2 hp two speed TriStar pump they would have comparable jet action and filtration, but much lower overall cost.  Let us run the numbers.  The installation of the two speed pump with a compatible timer is about $1460.  The electrical cost is much less.  $450 compared to $1200 per year.  Thus, the total first year cost is $1460 (installation) plus $450 (usage).  This works out to be only $1910 for the first year.  Thus, the two speed pump saves the home owner $240 in the first year.  Usage cost is more important than initial expense because it recurs every year.  This two speed pump will save the home owner $3339 in five years of usage. 

Why slower is better: When a pump runs at one half the normal speed, the slower water produces less loss due to friction. This works out to be one quarter of the head loss. Since there is less loss due to friction, the pump uses only one eighth of the energy at this slower speed. Half speed means half the turnover, so to achieve the same turnover as before, a low speed pump has to run twice as long. But don't think that this gets you back where you started, for twice as much time on low speed still uses only one quarter of the energy as does the original single high speed.  In the real world, however, you still need to use high speed for certain jobs.  You will still run the pump on high speed to run the automatic cleaner, the heater, and the spa.  I find that one hour a day on high is enough.  Thus, in a real world situation, I would expect an average two-speed pump to consume about three-eighths the energy that a single high speed pump would consume.

Energy savings and your electric bill: As the above calculations indicate, a properly setup two speed pump will use about 62% less energy than a single high speed pump. Your monetary savings will be greater. Southern California Edison charges for electricity on a tier-based system: the more you use, the more you pay. If you cut your usage by 62%, you will cut the swimming pool portion of your electric bill by approximately 75-90%.

Two speed benefits

• Saves Money  -- year after year
  
• Decreased  water velocity results in less wear and tear on heaters, cleaners, and filter grids
• Better filtration -- slower filtration traps finer particles in the filter with less pass through
• All day economical circulation -- no stagnant water in the hot afternoon
• Better for chlorinators -- Chlorinators only work when the pump runs
• Better for ozonators -- Ozonators only work when the pump runs