Cheaper solar water heater patented

Press, Volume CXIV, Issue 33454, 8 February 1974, Page 10

Cheaper solar water heater patented

• New Zealand Press Association > WELLINGTON, February 7. A solar water heater that can suppy 50 per cent of domestic requirements has been patented by the Department of Scientific and Industrial Research.

The D.S.I.R. has been working on a copper and steel solar heating unit since 1957. A scientist in the physics and engineering laboratory of the D.5.1.R., Mr R. F. Benseman. said the department had perfected a copper solar water heater in 1967, but this was shelved because of the cost of copper. The newly-patented heater, only 5 per cent copper, will cost about a third of heaters now on the market. The heating unit consists of 4ft bv 2ft glass panels called collectors. Simply, they are a glass plate on top of a darkcoloured plate that absorbs heat. Water will run through or behind the dark plate and receive the accumulated heat. Mr Benseman said that about 45 sq. ft of collectors would provide half of the hot water a normal house-

hold would use in a year. The units would be placed on the north side of a roof. The panels would be connected to the water-heating tank through a central-heat-ing pump with a heat-sensi-tive controller that would switch the pump on when the sun shone. LESS POWER Although the solar heaters must be used in conjunction with electric or gas water heaters, they could reduce demands for power considerably.

A quarter of all electricity is used to heat water, and half of domestic power con-j sumption is for hot water, i Until energy shortages? loomed, power was so in-j expensive that solar heating | units were uneconomic. Mrj Bensenman thinks that the department’s heater will be economic because of power cuts and rising power prices. “By the end of the century 7 , solar energy will be the cheapest form of energy,’’ he said. FIRMS’ INTEREST A number of large manu-i factoring firms have shown i interest in the heater and! now that it is patented the? Government can begin licens-’?' ing it for production. ;i The D.S.I.R. wanted to do another six months work on 1 the heater to develop maxi- . mum efficiency, Mr Benseman i said today. This could take much less time if industry ■ joined in the research. ii