The typical application of the closed loop solar pool heating system is for year round indoor pool operation. This system consists of a solar loop which is isolated from the pool loop. Year round pool heating (for colder climates) requires a collector area of approximately 80-85% of the pool surface area. Many factors contribute to this design, such as; geographical location, meteorological conditions, amount of lighting from windows, type of glass, depth of pool, wall insulation, etc. This system requires the installation of a heat exchanger and an additional circulator.
The closed loop solar pool heating system is composed of two independent loops.
The fluid in the solar loop is an antifreeze solution which is a mixture of propylene glycol and water (typically 50/50 % by volume). The propylene glycol water mixture is circulated through the solar collectors, and the shell side of the heat exchanger.
The pool side of the system circulates water through the filter, then through the tube side of the heat exchanger where solar energy is delivered to the pool water. The water then exits the heat exchanger, goes through the auxiliary heater where any additional required energy is supplied, and then returns to the pool.
The solar system is operated by a set point controller. If there is sufficient solar gain, the controller will activate the system, delivering energy to the heat exchanger, thus increasing the temperature of the pool water.
The advantage of the closed loop solar pool heating system is that the plumbing can easily be arranged to accommodate dumping of surplus heat during the summer and other times to the domestic water system or space heating system.