copper pipe
copper pipe in the tube,
no water running in the tube
transfer heat with alminum fin

heat  copper pipe

The heat conduction through the pipe is by the way of exchage of liquid and gas.The temperature difference is very low.Because of its high heat conduction feature and efficency,the pipe is used popularly in solar industry.

1.High heat conduction coefficient:is 2000-5000 times of matal materials.
2.High quantity of heat conduction:is 1000times od metal materials.
3.Low temperature difference:less than 4 difference in 2 meter long pipe.
4.Since no water in the vacuum tube, so it won't be damaged in the colde winter weaterh and  suitable for cold district.
5.When the sunshine is weak for several days,the water in the tank can be heated by electric heater which is automatically controller.But remember to shut it off before taking shower.