As Jae stated,
The MFG booklet on this unit is the guide…The MFG has the say on how this appliance is installed… not someone who is guessing on how this puppy should be installed… Warranty …gone… Efficiency …reduced…damage…occurring… :o
If it is NOT present at the FAU then we have a problem. These guides are there for this reason. The installer is instructed to leave these by the units for referral by home owner, tech or who ever needs to get information.
The “flues” are too low to the ground (grade) in my opinion. IF you are in a zone of the country that has significant amounts of snow then what is going to happen when these get blocked by the snow…:roll:
Looks like some “unprofessional” work here…
Building materials be in contact with these “pipes” ??
Terminations of these pipes in your pictures to low to grade…
Run length? “b” vent…I don’t think so…
I recommend having further evaluation by a HVAC professional…