How a Heat Pipe Solar Collector Works

Sunlight passing through the glass tube is absorbed by the black coating. The fins on the central copper tube heat up.

There are actually two glass tubes, one inside the other. The air space between the inner and outer glass tubes is evacuated, significantly reducing heat loss due to convection. Solar Collector

The liquid enclosed in the central copper tube has a low boiling point and turns into vapor. As heat rises, the vapor flows to the top of the pipe.

The top of the tube fits into a copper "nipple" in a stainless steel tank. The nipple transfers heat to the surrounding water in the tank.

This cools the tip of the copper collector tube, and the vapor condenses back into liquid. It then rolls down the side of the tube (which is cooler because it's not heated by direct sunlight) and returns to the pool of liquid at the bottom of the tube. As soon as it heats up, it begins to process again and again.

The beauty of a thermosyphon system is that it has no moving parts. It works by efficiently transferring heat from the absorber to the water, without your water coming into contact with any dangerous or toxic fluids. Even if a glass tube breaks, no harmful liquids are released into the environment or the water is contaminated.

Each tube functions independently, so if one breaks, the others will continue to work until you can replace the broken heat pipe.