About this product range:~ Habistat. Pulse prop. Thermostat Sophisticated pulse proportional thermostat, ideal for controlling higher power ceramic heaters. The function of this thermostat is far more sophisticated than the simpler on/off switching devices. It will very accurately control heaters & has a maximum load of 600 watts. A normal thermostat switches a heater on full power until the set temperature is achieved. It then switches the heater off completely until the temperature drops below the set value, when the cycle starts over again. The gap between the heater being switched on & then off is called hysteresis. It is between these points that the accuracy of the controller is assessed. The pulse proportional thermostat pulses electricity to the heater.