We're relocating our furnace/AC unit to the attic, which is also becoming conditioned space.
The HVAC guy wants to tie into the vent for the kitchen sink as the drain line. He says they "do it all the time". Is this a concern? Theoretically, it wouldn't matter, but I just don't know if when they are running PVC pipe for a vent line if they are as concerned about pitch, watertightness, etc.