If the thermostat has a day/night facility and you have a timer switch it should be ajustable by the red dial on the bottom of it so that the temp drops automatically. Mine is twisted fully to the left as i only need a 5 degree differential, twisting it to the right increases the drop. There should be a seperate lead that plugs into the left side of the thermostat box and then the plug from the other end of that has to be plugged into your timer and plugged in seperately to a socket. Took me quite a while to work this out too from the instructions! Hope it makes sense.