There is so much more that goes into today’s heating, ventilation, and A/C systems than what there was 100 years ago.
People seem to take for granted the heating, ventilation, and A/C systems of today, but you turned the oil furnace on, had a quick inspection done by an actual heating, ventilation, and A/C serviceman, made sure you had enough fuel in the tank, and heat came out of the HVAC duct.
The a/c component is finally cleaned, coolant levels get checked and filled, and then you turn the a/c on. You choose a temperature on the temperature control, and the home’s temperature can be the same year round, regardless of the weather. The heating, ventilation, and A/C serviceman does most of the work, even if the homeowner does need to change the air filters. I remember my father telling me how they would go to the island and option up coal for their oil furnace. There were only more than 2 or more when they were working. When their buckets were full, they would carry them back home. His father checked the fire more than 2 times a afternoon, so they would have heat all winter season long. During the summer, his mother would hang wet curtains up to the window. As the slightest breeze came through the open window, the wet curtains would dry, but cool the hot breeze. This was his a/c. He told me years ago, someday men wouldn’t need to honestly do much to check the heating, ventilation, and A/C systems. They would all be automated and run by computers. I have now lived long enough to automated, integrated computer systems that run heating, ventilation, and A/C systems, and entire buildings. It takes 1 guy to tend the computer, and if any work needs to be done to make repairs, they are only an iphone call away.