I am interested in infrared too but I'll have to have a contractor come look the shop over first. There are two overhead doors opposite each other and the one pretty much takes up the width of that end of the shop, using up a 14'X 18' wide chunk of ceiling in a 23' wide area with the opener taking up another 4'. The shop will be heated full time, if only above freezing when not in use. My other shop, 30'x32'x13' has a 75000 BTU hanging Modine that's been there maybe 25 years and was new when it was installed. It's been flawless. I keep forgetting to oil the fan so some day it will come back to bite me, but it does keep the shop any temp I want it to be even if it's -20 with a wind.
Thank you for supporting my negative opinion about a used hanging heater. Jim