Solar Water Heating: How it Works

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There are many types of solar water heater configurations. At Signature Plumbing we install the Closed Loop Glycol and the Closed Loop Drainback systems. These systems are best suited for the southeastern North Carolina region. Both closed loop glycol and drainback systems are effective and reliable.

Closed Loop Glycol

The major components that make up a closed loop glycol system consist of the solar collectors, the heat exchanger, circulating pumps, insulated piping, an expansion tank and a solar controller. The system is filled with a nontoxic propylene glycol antifreeze solution and pressurized. The fluid is heated in the solar collectors until the solar controller senses a predetermined variation in temperature between the fluid in the collectors and the water temperature in the storage tank. When the predetermined variation in temperature is achieved the controller turns on the pump and the fluid is then circulated through the heat exchanger and transfers the heat collected from the sun into the potable water storage tank.

Closed Loop Drainback

The drainback system primarily uses the same components as the glycol system. However, instead of using a pressurized glycol solution the drainback system uses distilled water that is stored in a reservoir tank on the return side of the loop. When the pump turns on, the distilled water is circulated from the reservoir back through the collector and heat exchanger, passing heat to the potable water in the solar tank. When the pump shuts off again, the distilled water drains back into the reservoir.