An introduction to the assessment of line-voltage thermostat performance for electric heating applications

The key indexes of thermostat performance in electric heating systems are explained. Response, offset, cycle time, and droop are introduced, as are basic methods for their measurement in field and laboratory. Correlation of field and laboratory tests is outlined, and brief mention is made of the NEMA (National Electrical Manufacturers Association) test box. Modern thermostat components, such as snap-action switches and shunt and series anticipators, are described, and two fundamental methods of modulation are introduced.