The difference between current & old A/Cs & boilers is large & is worth talking about.
When I was a kid, I enjoyed learning about the early stages of technology, recognizably in the world of Heating, Ventilation & A/C.
I learned about the first window A/C that was made from only a few unusual parts. Then I learned about the wood heater that was large in its day. After that I learned about central A/Cs & gas, oil, & electric heaters. A little later media air cleaners became a giant deal & every heating & cooling corporation wanted to get them on their shelves. I enjoyed learning about all of these things! Now that I am older, I adore working on air conditioning units & boilers & building them myself. I also work as an Heating, Ventilation & A/C specialist on the side for extra money. All this to say, I know a lot about both current & old Heating, Ventilation & A/C units, & I wanted to take a minute to compare them; Many people guess that technology has advanced so much over the years that an old A/C or heater would be unidentifiable to the current eye. This simply is not true. The truth is, old window A/Cs were structured much like current window A/Cs, just with easyr internal parts. Old window A/Cs did not, however, have any air filters which does make a giant difference in how well they work. Back in the day, central A/Cs were not really heard of except for in some of the more wealthy homes. Back then, commercial A/Cs were more of what several normal households have as their central A/Cs.