Thermosiphon Systems / Thermosiphon Systems

Roof Mounted Thermosiphon Hot Water Systems

Thermosiphon roof mounted tank systems differ from the other systems as both the solar collectors and the tank are mounted together on the roof. This style of system saves space at ground level and their simplicity makes them  efficient and reliable.

These systems operate on two main physical principles, principles most of us would already by familiar with:

  1. Dark objects absorb heat
  2. Hot water rises

When put together these principles form what is known as a “thermosiphon”. The dark, heat-absorbant surface within the solar collectors absorbs heat from the sun, heating the fluid that passes through it. As the fluid heats up, it rises to the top of the collectors and into the tanks where it displaces cooler fluid. The cooler fluid then flows into the bottom of the collectors and is heated again as before. This siphoning is simply a result of the temperature difference between the fluid in the solar collectors and the water in the tank, with a greater temperature difference resulting in a faster flow between them, and requires no mechanical input.

In open circuit systems the fluid in the collectors is water while in closed circuit systems a special antifreeze fluid, called Hartgard, is used. Closed circuit systems are recommended in frost-prone areas, which includes most of the Darling Downs.

When Hartgard is used, it is heated in the solar collectors and then circulated into a jacket around the outside of the water tank. This jackets allows for a heat exchange between the Hartgard and the water, with the cooled hart guard flowing back to the bottom of the collectors once the heat transfer has occurred.

All Solahart hot water systems come with a booster, either an in-tank electric booster or an in-line gas booster. This ensures hot water is always available on tap, even on cold, cloudy days.

To find out which Solahart solar water heater is best for you check out Solahart’s system selector or contact us for a FREE solar home assessment.

Next up: Have a look at solar hot water systems we have installed.