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Feature Article - April 2018

Expanding Pools of Knowledge

Control Maintenance Costs Without Sacrificing Safety

By Rick Dandes


Consider a Variable Speed Pump

The relationship between how fast a pump is pumping water and how much energy it takes relates to how much friction it is pumping against, Lachocki said. "When you reduce the flow of a pump by half, you reduce energy required by the pump by four-fold. In the olden days pumps generally had only one speed: on or off. If you install a variable speed pump, in the evening when the pool is closed and if the water quality is satisfactory, you can slow the pump down a little bit and you'll save a tremendous amount of energy. And you're still getting circulation throughout your system. Money is saved. It goes right to the bottom line."

"To reduce costs associated with water circulation and filtration," added Mike Fowler, commercial marketing/sales manager, of a Sanford, N.C., aquatic facility equipment manufacturer, "it is important to understand why pumps and filters consume large amounts of energy and what options are available to lower consumption. Replacing single-speed pumps to newer variable speed pumps is the perfect way to reduce energy consumption and thus operating costs. Another option is to add a variable frequency drive (VFD) to your existing pumps to increase pool pump efficiencies."

When it comes to commercial pools, Fowler explained, a three-phase pump can save an aquatic facility approximately 35 to 60 percent on its energy bills when compared with a one- or two-speed model. Further, when combined with a VFD, it increases the pump's efficiencies, as well as provides better energy savings. Even with a single-phase application, a VFD can be used with a three-phase pump to bring savings to those aquatic facilities.

Technological advancements in today's pool equipment, Fowler continued, "make it imperative for industry professionals to take the time to sit with facility managers to ensure they are achieving the water quality, parameter reporting and cost controls necessary to keep their facilities operating efficiently."

During the pump selection phase for an aquatic facility, the auxiliary features, such as spray pads, fountains and waterfalls, should also be considered, as it is common for them to use the pool's main pump. Some building codes require the use of a multi-speed pump, or in some cases, a separate pump for each auxiliary pool load, Fowler said. "Pumps for aquatic facilities are oversized by design—sometimes more than 20 to 40 percent bigger than they need to be. This is because many architects and engineers look at what is required, then pick the next size up to be sure the pump can handle the job."

Fowler offered a checklist of items to consider before opening your pool for the summer. Every one of these items, he said, can considerably help reduce your aquatic facility maintenance costs:

  • Replace pool pump with a newer, energy-efficient unit.
  • Consider a variable speed pump. VSPs with permanent magnet motors and digital controls can save up to 90 percent in utility costs compared to one- or two-speed pumps with induction motors.
  • If using an energy-efficient one- or two-speed pump, make sure it is sized to the pool's requirements. Affinity laws indicate the power demanded by a pump is proportional to the cube of the flow rate. "For example," Fowler said, "if the pump's flow rate is doubled, then its power demand is increased by a factor of eight. Therefore, it is important to utilize the smallest pump that is capable of completely turning over the pool water in an acceptable amount of time."
  • Reduce run time or speed on your pumps to lower energy use.
  • If using a one-speed pump, reduce filtration run time. In general, water needs to be circulated through the filter once every six hours for most commercial applications.
  • 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.
  • 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.
  • Keep intake grates clear of debris. Clogged drains require the pump to work harder.
  • To obtain maximum filtration and energy efficiency, backwash or clean the filter regularly, as required.

Supplemental Sanitation

While there is no silver bullet with regard to managing indoor air quality, ultraviolet light or ozone disinfection systems can significantly improve water quality by helping oxidize organic compounds, DeRosa said. "This, in turn, minimizes the introduction of disinfection byproducts into the air. Secondary disinfection system have become standards in new pool and spa construction and, if properly used, may help to lower overall chemical use, resulting in financial savings in addition to the environmental health benefits."

DeRosa also suggested exhausting indoor air frequently and replacing it with "fresh" outdoor air when possible. "While use of outside air can be a controversial topic in cold climates where there can be substantial savings by recirculating indoor air," he explained, "the challenge faced by pool operators is that recirculating pool air also recirculates the unhealthy chemicals that have evaporated into the air. This can lead to a buildup of DBPs (disinfection byproducts) and that telltale pool smell. A well-maintained and properly ventilated natatorium should not have a pool smell. Customers should not experience eye burn simply by standing on the pool deck or sitting in the stands. Swimmers should not be coughing during their workouts and complaining of asthma-like symptoms."

Improving air circulation and utilizing more source air rather than recirculated pool air laden with chemicals can help address indoor air quality, DeRosa said. "The ability to fully exhaust the air handling system and utilize source air may be especially important following large indoor swim meets or at aquatic venues with spraying or splashing elements."

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