The DT20RF digital thermostat with twin channel programmer controls the timing and temperature of your heating and hot water. You can set 3 separate time periods per day for your central heating and 3 for hot water per day, plus you can choose your target room temperature. The boiler-mounted receiver is activated remotely by the wall-mounted thermostat/transmitter. Communication via radio frequency (RF) Room thermostat provides temperature control Twin-channel facility times the domestic hot water function No wiring required Holiday function Also compatible with Greenstar system boilers if optional integral diverter valve is used