How well do you understand how furnaces work?

Hundreds of people see this at a local bank in the winter.

Now I'm not a furnace expert but I am a home buying expert, and I
think there is something wrong here.

Do you recognize the problem?

Update:

I looked up some installation instructions for the bank service person:

http://www.htproducts.com/literature/lp-166.pdf

Here is another:

http://www.dnmech.com/lit/good_dcvk_IO-619A.pdf