Fixing to install a hanging propane heater in my 40x56x16 shop. Not sure on the right size though. Located in northern Kentucky and wanting to keep shop at 65-70 all the time. It is pole style building with the 2" vinyl back wall insulation and steel ceiling with 6-8" blown in on top. Also has insulated doors. Was quoted from local company as needing a 200k btu. Does this sound too big?
Sounds like you are a little light on insulation. As a result, you probably will need that 200k btu. If you had more insulation, you might be able to use a smaller furnace but without knowing more about your building, 200k sounds right. Also, if you are light on insulation and want to keep it at 65-70, with a shop that size you are going to be using a LOT of propane. I'd say you'll need at LEAST a 500 gallon tank and probably want bigger.
I have a 30x40 shop building with 10 ft sidewalls and open rafters. It's well insulated with foam sheets and fiberglass. It heats very well with a 80k btu Big Maxx.
