Ours has been on since I came up to uni at the end of September (at least when Crazy Housemate has been in). Not looking forward to the gas bill at the end of the year, because Crazy Housemate thinks it's energy efficient to crank it up to 30 degrees then turn it completely off as soon as the house warms up, so we alternate between boiling and freezing. Winds me up because I'm sure she'd feel warmer if she'd do some exercise and dare to brave a vitamin or two!
Oops, I'm ranting... sorry! I'd better go and cool off XD