This is my first post son picked up 2 york 80k btu down flow furnaces at work for free. They worked fine,but they wanted an upgrade to 93% units. They were mfg in 1993. All the original books and paperwork are with them. My proposed use is in my newly built machine shop (on the farm).It is 1300 sq ft, insulated r-40 in cieling/r30 in walls. I will want to hold 40 degrees in there at all times during the winter because of electronics that are attached to the machinery. Humidity also cannot be an issue. The question is,are these "free" units worth bringing home for a look at them (they are 280 miles away,but I'm going there this w/e anyway) Or not? I had originally planned to install a 93% unit but figure I can by a lot of propane for the 2 grand it would cost to buy a new 93%.