Not to be super dramatic, but when i was 22 or so my house i was renting - a beautiful Victorian style house with a great big front porch and big beautiful rooms burnt down because our furnace was faulty. The furnace didn't so much catch fire as blow up. My bedroom was char. Items in my closet blew across the room and melted. I escaped with my life, my combat boots, and the clothes i was wearing. Everything else - gone. Everything. Books, toys, clothes, childhood memorabilia - incinerated. It was Horrible.
Take care of your furnace.