A lesson I've been repeatedly learning since buying an old house, is that many design decisions that seem dumb now were actually optimized very well for what was available at the time. It can be a real challenge to try to retrofit modern efficiency and comfort into a home that was designed for constraints and expectations of another time.

We recently replaced our furnace and found the footprint of the original coal-fired "octopus" gravity furnace, and learning about the operation of the old furnace makes the seemingly inadequate ductwork make more sense. Instead of a furnace blower (which hadn't been introduced yet at the time the house was built) the air moved around the house by convection and relied on a temperature differential between the center of the house and the outside walls. Hot air came up a few ducts in the middle of the house, and cold air came down through return ducts on the outside walls.

Unfortunately the chimney was also acting as a radiant heating element, and one of the upstairs bedrooms has become much colder since switching to the higher-efficiency furnace (which scavenges much more heat from the exhaust, and vents out the side of the house). Ultimately I'm sure the much more efficient furnace will be worth it, but there are trade-offs that will need to be addressed.