Conventional swimming pools and spas include a water recirculation system comprising a pump and a filter for filtering particles and debris from the pool or spa water. The water is also usually chemically treated to kill bacteria in the water. The rate of bacteria growth in the water is a function of, among other factors, water temperature, and therefore at lower temperatures the pump and pool filter can be run for a shorter time than is required at higher temperatures. However, some households maintain the same run time for the pool pump throughout the year, thus wasting energy and money. A typical 7.8A pool pump is driven at 220V and may run for 8 hours per day during the summer. Assuming current energy cost of 10 cents per kWh, a single pump costs $1.37 to run per day. Often systems comprise two pumps resulting in an expenditure of about $82 per month.
Most pool pumps are controlled by an electronic or electromechanical timer. The timer has the function of turning the pool pump “on” and “off” at designated times of the day to filter contaminants from the pool water. The “run-time” is the difference between the “on” and “off” times when the pool filter motor is running (consuming energy). A “constant-duty” timer turns the filter pump on and off at the same time every day, irrespective of the season. While some consumers adjust the run time of their constant-duty timer in the winter, and again in the spring, many forget to adjust the run time, resulting in running the pump unnecessarily. As an alternative, some households merely run the pool pump on a constant reduced run time during the winter months. Although this approach reduces the energy consumption to an extent, further savings could be made. Furthermore, some days during the winter months can be warmer than expected resulting in the pool pump being run for an insufficient duration allowing bacteria to proliferate. Conversely, during the summer months, cooler than normal days can occur resulting in unnecessarily long run times. It would be desirable to automatically adjust the timer to precisely controls run time throughout the year, with measurable savings.
An example of a pool recirculation control system is disclosed in U.S. Pat. No. 6,079,950 in the name of Seneff. This system includes one or two temperature sensors that detect the temperature of the water in the pool or the temperature of the recirculated water. This requires installing a temperature sensor that is remote from the timer circuits and installing the accompanying transmission system, either with wires or wirelessly with radio frequency. A controller operates one of a number of timer circuits that run the pump and filter for a duration in accordance with the sensed temperature. A first timer circuit runs the pump for a longer predetermined time period when the water temperature is sensed above a predetermined threshold. A second timer circuit runs the pump for a shorter predetermined time period when the water temperature is sensed below the predetermined threshold. A more sophisticated version of the system is disclosed that operates a single timer circuit for a run time that is variably controlled to be directly proportional to the sensed water temperature, i.e. longer run times for higher temperatures.
While the pool recirculation control system of U.S. Pat. No. 6,079,950 reduces the run time of the pool filter and pump in accordance with water temperature, the requirement of multiple temperature sensors and multiple timing circuits results in fairly complex system that is costly to produce and purchase and difficult to install. Homeowners prefer to handle daily maintenance like setting run times and adding chemicals without having to call a pool professional. It is desirable, then, that pool technology be simple and cheap enough for homeowners to install and use it without calling in a pool professional. Furthermore, with the number of existing pools, it would be desirable to upgrade existing pool technology by retrofitting existing systems, as opposed to installing entirely new ones.
Therefore, it is an object of the present invention to minimize the energy consumption of pool pumps and filters than the aforementioned prior art while maintaining the quality of the pool water. It is a further object to provide a device that can be retrofitted to existing systems and operated by a homeowner without resort to a pool professional.