Originally Posted By: mkober
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Did an inspection last week where I came across a gas f.a. furnace that had the appearance of being installed upside-down (no, I wasn’t on illegal substances). It was a newer unit, but the external name plate had been removed from the front–could have been a Heil or Lennox. There were several decals on the sides that were upside-down, and the two front service panels had been duct-taped to the sides to keep them from falling to the floor. The air filter was duct-taped to the (now) top of the unit, drawing return air from the entire room (the unit sat on top of a bump-out utility room/bathroom, in the vaulted ceiling space of the master bedroom). Heated air came out the (now) bottom into two painted steel stove pipes for distribution into the rooms. I’ve looked at a few counter-flow furnaces and more than a few updraft furnaces, but never one like this. So my question is: Is it possible for a heat exchanger to function upside-down? My money would be on “absolutely not,” but the unit was working (if only marginally–had a frozen toilet supply line the day before, just 12 feet away from the heated air outlet. Discretion being the better part of valor, I chose not to remove the service panels to monitor the inner workings (duct tape very dry, brittle), and of course emphasized in my inspection report the importance of having a qualified heating technician check the thing out. By this point in the inspection, I had already seen so many Rube Goldberg applications in the house (other furnace’s ductwork blocked basement access, etc.) that I was already “jaded.” .
Michael J. Kober, P.E. and H.I.
"NACHI Member and Proud Of It!"