A childhood belief about basements

When I was a little kid, my Grandmother had this huge old furnace in the basement. It was probably 70 years old, having been used to burn wood, then coal and then converted to gas. Well, this furnace was very big and had several big and rusted pipes coming out of it. It had a grill on the front (for loading the wood and coal) and when it got hot, the grill would glow red. My brothers and I were sure that the furnace was a monster and the grill was it's mouth.
To this day, I am nervous about going in to the furnace room, even though the furnace was replaced in the '70's.