Diagram of an optimally controlled heating and cooling system. The more things change, the more they stay the same. Most basic problems still exist which require continuing compromises. Better design can make considerable improvements in both efficiency of operation and comfort. Tishler's comments are directed toward forced-air heating and cooling systems, using a common distribution system for the convenience of central filtering, humidifying, and the efficient introduction of fresh air.
Thermal losses determine the rate of temperature change between cycles when the thermostat is off.
The system would be controlled continuously when the thermostat is both in the on and off conditions, compensating for the actual losses and operating more efficiently. More moisture would be removed from the air during cooling, resulting in comfort at a higher thermostat setting. Continuous control would eliminate the cold blast when the system is activated as well as any uncomfortable conditions between cycles. In addition, the large pulse of heat would be eliminated in the heating mode when the thermostat turns on. With this optimal system, the air velocity would remain constant and the temperature of the air regulated.