DC Pool Pumps

DC pool pumps, 1/7 HP or 100 Watts, are installed in tandem to the existing AC pool pump (typically 2-3 HP). During the filtration cycle or while moving water through the pool filters, DC pump will be turned on to save energy. Since the pumps remains in this mode most of the time, average usage will remain close to 100 watts. The AC pump will be turned ON only if the water features such as spa or waterfall etc. needs to be operated. Thus, by using a 100 watt pump most of time instead of a ~1.5 kW pump, the savings potential is huge for this technology. In addition, the noise levels are reduced because the pump is a DC brush less motor.

The typical public swimming pool in California uses an oversized single-speed alternating current (AC) circulation pump to meet regulations for providing a clean and healthy pool. The conventional energy efficient retrofit for the AC pump is a variable-drive frequency (VFD) pump. However, VFDs require the installation, programming, and maintenance of a sophisticated control system for their optimum operation, which tends to translate in a significant investment of time and money. A Southern California Edison (SCE) team conducted this Emerging Technologies (ET) field assessment to evaluate a new pool pump concept: installing and operating a low-power, low-flow direct current (DC) circulation pump in parallel with the existing AC pump. The team set up the field test to evaluate the new concept at three public swimming pools in two apartment complexes in Fountain Valley, California, a city within SCE’s service area. A key element of the evaluation was determining not just energy and demand savings of the AC and DC parallel pump system, but also the ability of the system to meet California regulations. In so doing, the team was cognizant of the need to properly identify the regulations applicable to the pools under test based on their vintage. Two codes that govern the construction and operation of public swimming pools in California are as follows: -2013 California Code of Regulations, Title 24, California Building Code, Part 2, Chapter 31B (2013 CCR-Title 24): All public pools must have the capacity to completely recirculate (or, complete one turnover of) all the water in the pool within six hours. -California Code of Regulations, Title 22, Social Security, Division 4, Chapter 20 (2014 CCR-Title 22): All public swimming pool recirculation should be operational when pool is open to the public or any additional time that may be necessary to maintain the water in pool in clear and disinfected condition. The flow of the water in this regulation should not fall below the requirements listed in Section 3124B of Title 24 Pools built prior to 1982 may use the pre-1982 code requirement, which requires one turnover every eight hours of operation, while maintaining continuous recirculation during pool open hours.