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For homeowners living in cold climates where freezing temperatures are possible, a freeze-proof solar water heater is a necessity. SolarTown's selection of solar water heaters for cold climates includes active closed loop, passive drainback, and passive thermosyphon systems from brands such as EagleSun.
Choosing a solar water heater for your home will depend on how cold your climate gets as well as whether you want an energized circulation system. An active closed loop system protects against freezing by circulating an antifreeze fluid (rather than domestic water), ensuring you are never without warm water, even in cold weather.
Passive solar water heaters, which rely on the tendency of fluids to circulate naturally without assistance from an energized pump, guard against freezing by incorporating either a drainback or thermosyphon add-on to the entire system.
In a thermospyphon system, the storage tank is installed above the solar collectors indoors to protect it from freezing. These systems use either water or an antifreeze fluid which is circulated through the piping passively.
A passive solar water heater with a drainback system, on the other hand, will automatically empty the heat transfer fluid out of circulation whenever there is a threat of freezing. This ensures that the fluid (commonly antifreeze) does not freeze while in the outdoor piping.