it had an ancient westinghouse AC compressor that hadnt been used since the early 90's, and a highboy in the basement that we had service records starting in '82. we replaced it with a 95% efficient furnace and a new AC compressor both made by Amana.
the furnace vents through the the front of the house, instead of the chimney like it used to. the basement has two (soon to be replaced) windows, and 3-4 more vents along the back of the house in the crawl. 1800sqft house, on top of a 900sqft basement, hopefully thats enough vents?