I bought this unit for the high efficiency as well as good luck with Sterling products before. I put a GG series in my other shop that has worked perfectly since day 1. After spending so much money on the hu100 I expected it to work perfectly as well. First off it was shipped without the condensate drain, the transformer was loud and needed replacement, and the gas valve did not work properly. Once these issues were resolved it seemed to work fine. The next day it would fire up as it should but the blower fan would not kick on causing the unit to overheat and trip the limit switch. After a lot of trouble shooting I found the factory connections on the blower to be loose. The crimps were only on the plastic sleeve, not on the metal crimp itself. Once that was resolved it has now worked flawlessly for 24 hours. I expected much better quality for the price of the unit. I keep wondering what is going to go wrong next? I do have to say that with all of the issues acfgreenhouses.com and mesteska have been great at sending out the replacement parts.