Active Closed Loop Solar Water Heating System

Flat plate type.

Active closed loop solar water heating system.

Temperature water heat. Most new solar homes feature a variation of one kind or another. Active closed loop solar water heaters. Heat transfer fluids are used to transfer heat to the domestic water by way of a solar heat exchanger.

Glycol or some equivalent antifreeze fluid fills the collector and associated routing pipes. There are two main types of solar hot water systems. This is the simplest of the active systems which are very popular in florida usa and in tropical climates all over the world. Closed loop active antifreeze systems are the most versatile and failsafe of all the solar supplemental water heating systems.

In active solar hot water heaters with closed loop or indirect circulation the fluids are designed to remain within the plumbing loop at all times. A closed loop often referred to as a glycol or anti freeze system a drainback system. Used for residential and. Open loop active direct solar water heating systems mainly for domestic utilization these systems are used in tropical settings where freezing never occurs.

Because the array completely drains water can be used in the solar loop which avoids the need for double wall heat exchangers demanded in some localities. Closed loop systems use a heat transfer fluid to collect heat and a heat exchanger to transfer the heat to household water. Instead of relying on glycol for freeze protection this system allows all the water in the array to drain back from the array and into a storage vessel in the solar loop when the pump is turned off. The type of system affects overall system design and each type of system has strengths and weaknesses.

In this system potable water is drawn directly from the storage tank and circulated through the array to be heated and returned to a recirculation port in the tank. A special water heater tank incorporating a heat exchanger works in conjunction with one or more flat plate roof mounted collectors. They are popular in climates prone to consistent freezing temperatures. 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.

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.