How to change old thermostat to smart?

To change your old thermostat to a smart one, you'll need to follow a few steps. First, check the compatibility of the new thermostat with your current system by verifying the voltage range in the instruction manual. Next, turn off the power to your heating system, either by switching off the relevant switch in your fuse box or the general power switch near the wiring centre. Then, remove the old thermostat by taking off the front cover and disconnecting the wires from the screw terminal. After that, place the base of the new smart thermostat, which may involve drilling new holes or using the existing ones, and connect the wires to the corresponding screw terminals, taking care to match the colors (red for power, white for heating, green for fans, yellow for cooling, and blue for the common wire). Finally, place the front of the smart thermostat onto its base, turn the power back on, and follow the on-screen instructions to get your devices connected and running.