Closed Loop System Solar Water Heater

The primary difference between the two system types is that water is used for heat transfer in a drainback system and a glycol solution is used for heat transfer in a closed loop system.

Closed loop system solar water heater.

Active closed loop systems use electric pumps valves and controllers to circulate the heat transfer fluid usually a polypropylene non toxic unlike polyethylene glycol water antifreeze mixture through the collectors. There are two main types of solar hot water systems. A closed loop often referred to as a glycol or anti freeze system a drainback system. Heat exchanger to exchange the heat between the hot solar panel antifreeze and the clean potable water.

The glycol is separated from the potable water by means of a heat exchanger that transfers the energy from the array into the storage tank. Closed loop systems use a heat transfer fluid to collect heat and a heat exchanger to transfer the heat to household water. Closed loop active antifreeze systems are the most versatile and failsafe of all the solar supplemental water heating systems. Sized for family load.

Most new solar homes feature a variation of one kind or another. A special water heater tank incorporating a heat exchanger works in conjunction with one or more flat plate roof mounted collectors. Glycol or some equivalent antifreeze fluid fills the collector and associated routing pipes. Indirect closed loop solar glycol systems use propylene glycol as the heat transfer fluid in the solar array to overcome issues of freezing glycol can tolerate 60f in high concentrations and eliminate scaling.

A typical closed loop solar water heating system consists of.