All thermostats allow some variation of the temperature from what you set it at before it will turn on. Typically this is 1-2 C, meaning that a thermostat set to 22C will not turn on until the temperature drops to 20 or 21C. Many thermostats allow you to configure the variance – you would have to refer to your manual.
J&L – if your bedroom is above the garage, and you find the temperature swings like that, I guarantee that you are lacking insulation in the ceiling of the garage, or the attic, or both. I’d recommend you have a look in the attic, and possibly drop the ceiling in the garage to check for insulation. It would not be that expensive to have the ceiling re-dry walled. If you home is still under warranty, then get Mattamy to do it.
The other thing I recommend is a thermostat that allows you to program the furnace fan independently of the heat. You will not find these in-store, but are easily ordered online or through a professional. I got this one for about $100 online, and HIGHLY recommend it. You can configure it to run the fan on circulate mode, which means that the fan runs for 5 minutes every 15 minutes, circulating the air in the house even if heat isn’t required. It will eliminate those hot/cold zones in the house, and makes the whole home more comfortable. In the summer, my upstairs is the same temp as downstairs, and vice versa in the winter.
http://yourhome.honeywell.com/Consumer/ ... ostats.htm