Pyongyang, August 29 (KCNA) -- The Heat Engineering Institute of the State Academy of Sciences of the DPRK has developed a solar water heater for home use.

The solar water heater is based on gravitational pipe. It, quicker than the plate water heater in heat exchange, keeps water pipe from being frozen even in sub-zero temperature.

It is easy to manufacture as its structure is simple.

Once set up, it can always provide hot water, not subject to seasonal restriction.

A heating plate of one square meter is enough to keep 70-80 liters of water and that of 1.5 square meter 100 liters of water as warm as 40-45 degrees centigrade.

Researcher O Kyu Hak told KCNA a house which had used coal to heat water can save 500 kilograms of coal a year by use of a 1.5 square meter water heater.

The solar water heater has already proved effective in Taedong County, South Phyongan Province, and other areas of the country.

It won a prize at the 25th National Festival of Science and Technology.