| ‘GREEN’ CIRCULATION CHECKLIST |
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| 1. Replace pool pump with an energy-efficient unit. 2. Consider a variable speed pump (VSP). VSPs with permanent magnet motors and digital controls can save up to 90 per cent in utility costs compared to one- or two-speed pumps with induction motors. 3. If using an energy-efficient one- or two-speed pump, make sure it is sized to the pool’s requirements. 4. Reduce run time or speed to lower energy use. 5. If using a one-speed pump, reduce filtration run time. In general, water needs to be circulated through the filter once every 24 hours. 6. If using a two-speed or VSP, use the lowest speed to appropriately circulate the water. Reducing speed saves more energy than reducing run time. 7. Run the pool’s filtration system during off-peak hours when electricity demand is lower (generally between 8 p.m. and 10 a.m.). Install a timer or control system to automate hours of operation. 8. Keep intake grates clear of debris. Clogged drains require the pump to work harder. 9. To obtain maximum filtration and energy efficiency, backwash or clean the filter regularly, as required. |
Pump selection tips
- Determine flow rate in litres per minute (lpm) (gallons per minute [GPM]).
- Calculate total dynamic head (TDH), which is the pressure head difference between the inlet and outlet of the pump, to account for friction loss. Adding 6.1 m (20 ft)/head for a dirty filter is optional. Friction loss is generated by each fitting, valve, filter, heater and chemical feeder that is part of the pool’s circulation system.
- Refer to the pump’s performance curve to select the preferred unit.
- Locate the required horsepower of the pump by plotting GPM vs. TDH. (If the plotted point falls between two pump sizes, select the next larger pump size in terms of horsepower.)
- Do not oversize the pump. Choose the best pump available for the facility’s flow rate requirements (i.e. do not install a 20-hp pump where a 10-hp pump will suffice just because that is all that is available). If the preferred pump does not provide a proper fit, consider a different pump model.
- Verify the selected filter can handle the system’s flow rate and be sure the minimum backwash flow rates can be achieved.
Speed is a factor
Historically, pool pumps with induction motors, which only operate at one or two speeds, have drawn more energy than is required to circulate pool water. These units must constantly operate at high speed to perform their most demanding jobs (e.g. running a waterfall or pool cleaner). However, it takes far less power to simply keep the pool water filtered—a difference single-speed pumps cannot address.
Where variable speed pumps (VSPs) differ is in their ability to be programmed to operate at set speeds to deliver the correct flow rate for each task they perform. This enables an aquatic facility to reduce energy consumption and increase savings.
They can also be programmed to achieve turnover times of exactly six hours, even if the filter is dirty. This allows motor speed, power and energy to be reduced during times when the filters are clean, instead of sizing the pump to assume worst-case operating conditions.
Some VSPs have built-in, constant-flow software, which maximizes the advantages these pumps have to offer, as it will automatically adjust its speed to deliver the required flow rate for each programmed task. For instance, if an arcing laminar water feature requires 151 lpm (40 gpm) to produce a smooth 1.8-m (6-ft) arc of water, the pump will automatically ramp up its speed when it senses resistance in the circulation system (e.g. as the filter accumulates dirt) to continually provide the proper flow rate. With other pump types, the water feature will gradually throw a shorter arc of water as the filter gets dirtier.
It does not matter what type of pump is being used; slower pump speeds save energy. It also dramatically reduces noise levels, as well as wear and tear on the other pool equipment in the circulation system.
