Non-pressurized solar water heater

Thermosyphon solar water heater allows the potable water to circulate directly through the collector and tank, resulting in efficient heat transfer as no heat exchangers are required. The storage tank is made from food-grade stainless steel by automatic welding, which efficiently avoids the leaking problem. It is a simple and safe solution to get heat power from the sun.


  1. Outer tank material: SUS304-2B, thickness: 0.41mm; Inner tank material: SUS304 2B, thickness: 0.5mm
  2. Evacuated tube material: high boron-silicon glass 3.3, the coating of absorber: CU-SS-AL/N/AL, dimensions: OD 58mm x length 1800mm, thickness: 1.6mm
  3. Heat efficiency: absorbing rate: 92-96%, emission rate: 5%±2%, 2.5 hours to boiling point, heat preservation: 72 hours

Compact solar water heaters rely on the natural circulation of water between the collector and the tank or heat exchanger. In this type of installation, the tank must be located above the collector. As water in the vacuum tubes is heated it becomes lighter and naturally rises into the tank, meanwhile, cooler water in the tank flows down to the bottom of the vacuum tubes, causing circulation throughout the system.

This non-pressure solar system relies on a natural Principle –”Thermo siphon”. As the sun’s rays hit the evacuated solar collector tubes, the temperature of the water in the tubes rise to certain heat levels, making the water less dense or lighter. The hot water naturally moves up to the top of collector and throughout evacuated collector tubes converting to the storage tank. The colder water in the water tank then moves down to the bottom of the collector. This process is continuous thermal processing, and 100% natural in heating water from the sun with evacuated specially designed vacuum tubes.