As I've gotten older, I've come to associate the hum of the heater with safety during the winter season. When I was living with my girlfriend's mother, the heater used to kick on every night while we were cozied up in bed; it was a low drone that negated the wind sweeping past the windows. The furnace meant that, despite the harsh conditions of the outside world, we'd be safe and warm inside.
But when I was younger, the furnace was a loud monster that belched hot air from the vents in the house. My parents' house has multiple vents that pump out air and dust, and on one of them is a chain that allows the user to pull the vent closed for whatever reason. It used to rattle and shake when the heat kicked on; the blower was loud and boisterous; the vents were dusty and impenetrable. It was a scary thing for a little boy.
Especially when I saw Home Alone for the first time, that is. As Macaulay Culkin makes his way down to the basement, I found myself tightening up - basements were scary back then, and he was alone without his parents were anything to go wrong. More than ever I was able to put myself into the shoes of the character because we had a similar cellar.
As you can see, someone had some fun with this scene.
That did it for me - I was sufficiently freaked out, enough to force my parents to shut the film off. "It's just a furnace!" they said, "Like the one we have downstairs." But I knew for a fact my furnace didn't open its mouth without human labor - or did it?