We’re having the furnace replaced today. The old one was 20 years old, and while it hadn’t failed yet, a number of people who know about furnaces have looked at it and told me that it should be replaced Real Soon Now. Last winter I watched the neighbors enduring a furnace replacement during rather cold weather. I’d really rather avoid doing that, so the new furnace is going in today.
This event brought back memories of the furnace in the house that I grew up in. It burned sawdust. There was a room in the corner of the house that served as a huge storage bin. Once or twice a year (to my recollection) a huge truck would arrive and blow a load of sawdust into the room through a covered hole in the wall. After that the house would smell of sawdust for a few days.
The furnace itself had a big hopper that my parents filled with sawdust in the morning. The sawdust trickled into the firebox through a slotted grate. When the temperature fell, the thermostat turned on a motor which pulled a chain that opened a little vent on the front of the firebox, allowing the fire to burn more rapidly and creating a draft to pull the heat through a manifold, from where it was blown through the ductwork like any other furnace. (You can tell that I found this fascinating as a child; I still have vivid memories of it.) The fire would burn as long as the hopper was full. If it went out, it had to be restarted with newspaper and kindling, just like starting a campfire.
Such a contraption only made sense in the northwest during the 1960s and 70s, where there was an ample supply of sawdust as a by-product of the lumber industry. Eventually it had to be replaced because they started shipping all of the top-grade sawdust to Japan where it was made into particle board. After that the sawdust that was delivered to us was wet and resinous, and the accumulation of resin in the flue started a fire in the chimney. In retrospect it was kind of a neat invention, although obviously it had the same emissions drawbacks as any other woodburning source of heat, and perhaps more.