Ctom, is it a blue flame type propane wall heater? I put one in my garage shop when I was in Drakesville, Iowa. It worked very well. The only drawback was the moisture it created on the windows. it kept my 350 sq. ft. shop very toasty. I bought mine used from a man who purchased a bigger unit for his wood shop. If I remember correctly it, mine was a 20,000 btu also. You'll love it.