The T4 is a wired programmable room thermostat designed to control the efficiency of heating and cooling systems and to maintain comfort temperatures when you are at home or outside.
With its superior TPI control algorithm, your combi reaches the desired temperature by operating for a shorter time and consuming less energy. Temperature fluctuations are minimized and your boiler will not be fired unnecessarily, unlike 0.1 degree precision thermostats.
It controls the flame modulation of your boiler in the most efficient way by using the OpenTherm communication protocol of modulated boilers.