Hell, NO! That has to go. What a complete moron installation. Combustion gases and condensate drip in front of the door isn't going to work. Depending on conditions you could also get an ice ball on the ground in front of the door.
Since there is only one pipe visible, I would look at how/where they are pulling combustion air for the unit. Probably from the closet that the unit is in? Is it big enough or are there transfer grilles on the wall, louvered bi-fold, etc. What is the set-up or is the unit going to starve for combustion air?

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Accurate Inspections & Consulting, Inc.
847/736-9975
Markus Keller