How Solar Water Heaters Work

One of our most popular units for domestic water pre-heating, the evacuated tube system, consists of an array of glass vacuum tubes feeding into aheavily insulated, stainless steel lined 40 gallon header tank. The diagram shows the heat pipe system in which a small amount amount of glycol within an inner copper tube vapourizes and carries the heat into the tank where it condenses and returns in a continuous cycle as long as there is a semblance of sunshine, even on a relatively cloudy day, and regardless of the outside temperature.

Each tube has a copper heating element which is inserted into the tank. No water circulates in the tubes themselves.

There are two secrets to the efficiency of evacuated solar tubes: the high technology coating on the inner tube absorbs nearly all of the sun’s energy, and the vacuum between the absorber and the outer tube means that no heat can escape by conduction or convection.

Collector tubes can work all year round in cold climates. As cylinders, the tubes track the sun across the sky. Low heat loss and high efficiency mean that even days with little sun will produce some hot water. In sunlight the unit produces 5000 BTU/hour.

The system is intended to pre-heat water entering the regular domestic water tank, and also works effectively with on demand-type hot water systems. In some instances, such as off-grid summer cabins, this unit may even be the sole source of hot water. No pumps or other electrical equipment is required. The system also works well to preheat water for hot tubs, swimming pools and radiant floor heating.

Please contact us to discuss the ideal system for your site.

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