This is the most prevalent and popular solution to get access to hot water supply at low cost. This Eco-friendly technology is widely used around the globe and provides an excellent alternative to conventional heating systems, with absolutely no running cost. Therefore, installation costs are extremely low due to basic hardware requirements. Thus, thermo siphons systems may be foreseen as individual water heating device in apartment houses, individual rooms/resorts, standing as a relevant alternative to costly conventional central heating systems.
How does it work?
A thermo siphon solar water heating system has a tank mounted above the collector. As the collector heats the water, it rises to the storage tank, while heavier cold water sinks down to the collector. The system will be mounted on top of the roof with a dedicated and adapted structure.
Each system is adapted to the local scenario, and a relevant product for India not suitable for China. Higher price generally means better reliability and durability, varying 3-4 years to 15 years lifetime. Materials/workmanship quality and terms of warranty are subjected to high variance.
Technology Basics –
Different types of systems are widely available in the market, with significant gap in quality. The most popular one in China uses evacuated heat pipes, whereas the most common one uses flat collectors. These systems exist either with or without heat exchanger (direct/indirect or open/close loop systems), which allows installation in regions where frost may occur. A household/hotel apartment with 4 people will be suited with a system of 300 litres and 3 to 4 square meter of collecting area on the roof. An electrical back- up is recommended to prevent hot water shortage during low irradiation periods or temporary greater consumption. System capacity starts form 60L to 1000L.