I have recently bought a heat pump/gas dual fuel system. The installer told me that the system would automatically switch to gas when the room temperature dropped more than two degrees below the thermostat setting. I have two questions:

1. Does this mean that if I lower the thermostat setting at night, then raise it more than two degrees in the morning, the gas will come on? If this is so, is there a way to prevent this, short of inching the thermostat up two degrees at a time?

2. Is there an energy saving by lowering the temperature at night, or is that offset by the greater heat requirements to warm it back up, since not just the air inside, but the house itself cools down? What about a longer period at the lower temperature, such as warming up the house only in the after-work-to-bedtime period?

Thanks for your help.