We had an oil delivery yesterday, and a few hours later we started hearing what sounded like someone hitting a bass drum. I went down to the furnace room, and the flap on the aluminum flue would open each time the drum was beaten. By 9:00pm, I realized we weren’t getting any heat. By this morning, it was 56 degrees in the house. I’ve contacted our furnace guy, who I think will be over sometime today when he can fit us into an already busy schedule. Anybody recognize this? Do you think it is connected to the oil delivery?