The ST100 thermostats are designed to provide automatic time and temperature control of heating systems in homes and apartments. It’s compatible with 230V on/off appliances such as gas boilers, combi boilers and heat pumps. Also works with zone valve applications but not with electric heating (240V).
The ST200 is for wired installations or table stand installations (wireless). It consists of a thermostat and a Receiver box. The ST100 is specifically for wired installations and include only a thermostat.