Hi
Just wonder if this connection would pose any problem. The HVAC condensation drain line is connected to a plumbing vent stack in the attic.
First ask yourself what are the requirements for a condensate line .
Yes it is above cross contamination concern.{as far as liquid]
Now let me ask you is the line at the required 1/4 inch per foot ?
Does it have a trap ?
Is there an air gap?
Why are they required ?
A Plumbing vent can not terminate into a attic and with no trap would that not be the case ?
Have a pic of the other end at the unit ?
[guessing it is a horizontal unit in the attic here ]
Sheesh.
Yes it’s a problem. Sewer gases, which are deadly, now have a path back into the HVAC system ductwork. Call it out.