I don't keep my shop heated all the time but here is what I've found- My shop is 28 X 30 with 12' ceilngs. It is well insulated but I have 2 uninsulated garage doors 1- 10' X 10' and 1- 8' X 8'. I have the 75K heater. When the outside temp is about 40 degrees, it takes about 15 mins. to raise the inside temp to 60 degrees. The heater will run about 5 mins. every hour to maintain 60 degrees. I figure the heater will run approx. 1 hour and 10 mins. on 1 gal. of propane which is about $2.50 a gallon right now. Last month I used 4 gallons and was out in the shop quite abit. Hope this helps.
