I Need to Reduce My Electric Bill

With fast rising electrical rates in various regions of our nation, many pond and water feature enthusiasts are becoming concerned with enormous electric bills.  For some, this increase is so drastic they feel major changes in their system’s are warranted.  I will use a comparison between using high or low rpm pumps to address their justified concerns.

A typical koi pond could be arranged as follows: 6000 gallon pond; 5’ high waterfall; bead filter and uv light.  This configuration requires a flow rate of 100 gpm to maintain a once per hour turnover rate.  For brevity’s sake, we will size this system as follows: the friction loss through the pipe, valves, elbows, and fittings is equal to 10’ of friction head.  A 5’ waterfall has 5’ of static head.  The combined bead filter and uv light in series has 15’ of pressure head for a combined total of 30’ total dynamic head (tdh).  This means, I need a pump(s) capable of moving 100 gpm to a height of 30’.  This height is considered a medium head and in most cases would require a high rpm pump. 

Performance specifications vary between pump manufacturers so I will use PerformancePro Pump data for this illustration.  The Artesian model (A1) true self-priming, 1 horsepower, high rpm pump (3450 rpm), will provide approximately 113 gpm @ 30’ head.  This pump requires 14.8 (a) amps at 115 (v) volts or 7.4 amps at 230 volts.  The following formula will provide a very close average for monthly electric cost. 

(V x A = Watts / 1000 x kilowatt rate x 24 hours x 30.4 days)

Kilowatt rate                       Monthly cost

.10                                       $124.18

.14                                         173.85

.18                                         223.52

.22                                         273.19

Now we will consider the same system originally built or redesigned to operate with two low rpm pumps running in parallel.  The Artesian model (A1/3-56) true self-priming 1/3 horsepower low rpm pump will provide 73 gpm @ 15’ of head on 3.7 amps at 115 volts or 1.85 amps at 230 volts.  Together these two pumps will deliver 146 gpm @ 15’ head.

Kilowatt rate                     Monthly cost per pump                    Cost x 2 pumps

                .10                                       $31.04                                          $62.08

                .14                                         43.46                                            86.92

                .18                                         55.88                                           111.76

                .22                                         68.30                                           136.60

Kilowatt rate                     Monthly Savings                               Annual Savings

                .10                                      $62.10                                            $745.20

                .14                                        86.93                                            1043.16

                .18                                      111.76                                           1341.12

                .22                                      136.59                                           1639.08

Operating cost savings of this magnitude justify serious consideration toward original design or reconstruction with a goal toward increasing your recirculation flow, while lowering the head requirement of each pump, thus obtaining short and long-term electric cost saving.

Since system designs and requirements are so variable, I can only provide general options that may be available to reduce the head requirements of your system: increase the diameter of the pipe wherever possible; use flex hose to reduce the number of elbows; redirect your flow to reduce the friction loss per run; redirect your flow to reduce your pressure head, plumb a second pump on an independent system.  Engineering assistance is available at PerformancePro Pumps 503-356-5888 at no charge. 

Finally, let’s examine the benefits beyond cost savings from building a system with two low rpm pumps instead of one high rpm.  First, pump noise will be significantly reduced.  Second, it guarantees a backup pump for koi safety.  Third, you will gain the option of running only one pump at various times.  Fourth, once the initial expense of adding a second pump has been realized, your total electrical savings will continue to increase month after month. 

If you consider a 21% increase in your flow rate per minute while gaining a 50% reduction in your pump operating cost a good thing you also may decide it is time for a change.

Lee Breidenbach

Sales Manger

PerformancePro Pumps

lee@PerformanceProPumps.com
http://www.PerformanceProPumps.com