ABSTRACT
The control system incorporates a manual selector switch which may be set at any one of three positions: ‘heating only’, ‘cooling only’ and ‘heating–cooling’. The entire experimental heating–cooling system was fabricated and installed by a university mechanic and two paid student assistants. The performance of the heating–cooling system has been monitored continuously from 1 July 1959 to the present writing. The entire roof of the building is a large flat-plate heat-exchanger, made of copper sheet with built-in water-circulating tubes. The roof panel is painted a dark green, a colour which is aesthetically more attractive than black but reflects very little more solar energy than the ordinary black paint. When set at ‘heating–cooling’ the system operates to store solar-heated water in the upper tank and night-cooled water in the lower tank. The operating cost of the system (electrical energy at 2.5 cents per kW h) is about $215 per year.
