Solar Thermal Drainback Systems
Solar thermal drainback systems eliminate a lot of the problems related to other systems. They are simpler than thermal glycol based solar systems, but with many of the same system principles. Glycol systems are considered the most reliable for northern states and Canada where the system will be exposed to long periods of freezing temperatures. Solar thermal drainback systems are especially advantageous for:
- solar thermal systems in temperate climates. Eg. N. Carolina
- people with hard water from their local utility
- those who want a simpler solar thermal system
This is an indirect system, in that it uses heat exchange instead of directly heating water. However (different from a glycol-based solar thermal system) this heat exchange system has water in the piping; this water, in turn, heats other water inside the tank. This system is esteemed by some in the industry as the most efficient solar thermal system, using the same principles as a glycol-based solar thermal system but with less system components.
This system's controller activates the pump when the temperature of the solar collector panels becomes higher than that of the water in the hot water tank.
The solar thermal drainback system is simpler than the Note:
The drainback system is significantly different from other collectors of solar thermal called a draindown system, which is problematic and has gone out of vogue in most places.
Note: The drainback system is significantly different from other collectors of solar thermal called a draindown system, which is problematic and has gone out of vogue in most places.