I live in a 60’s house out in the country in the Midwest and I’ll tell ya that my furnace is amazing. It’s original and was just maintenanced and not due for a checkup until 5 years. That being said we do have dated windows, 2 currently with cracks in them. The home is a 2-story with the first floor underground. The furnace is great at heating the main floor but sometimes our basement floor gets a little nippy.We run off of well water with the home being built entirely out of cinder block or brick. So once a room gets cold, it will stay that way for a while. With these places on opposite sides of the hallway, we don’t even need to heat the 3 bedrooms downstairs. This helps the furnace as we have the sensor upstairs for temp, and with these downstairs on their own sensors/screen lock, my family can sleep with doors open or closed and not have to double up on blankets when we get hit by a blizzard/deep snow