The controller was set to switch on the heating coils whenever
the temperature in the drying chamber fell to more than
one degree below the set temperature and to switch off
the coils as soon as the drying chamber temperature exceeded
the set temperature by more than one degree centigrade.
Thus the temperature controller could maintain
the set temperature to within ±2 C using the signal
from a T-type thermocouple inserted into the drying
chamber.