This furnace is installed in my 25'x65' home workshop, a metal building poorly insulated. The thermostat is 30' from the furnace. It's mounted on a steel stand 3' off the floor. On a 40 degree day it raised the temperature 15 degrees in about 2 hours, without any duct work (it hasn't been installed yet), therefore I think it will be plenty large enough to keep the shop cozy on very cold days. Quality appears very good, and everything worked properly the first time it was used. With an unlimited amount of free firewood on my property, it will save me a lot of money compared to using propane! So far, it's just what I expected.