I have a 140,000 btu up flow that sets at the end of my work bench ( 2'x2'). It's been there since 1991, cost $12.50 (got two for 25 bucks), it's easy to service,heats 38x68 Morton building,and costs less than $100.00 a month in the dead of winter. I work in shop every day,and temp is at 60 all...