Contractor just installed a Lennox SLP98V furnace, with an AC-coil directly on top of it. They used 3/4" PVC tubing to drain the AC pan across the top of the furance, then straight down. BUT, they TIED IN the furnace condensate drain directly into the AC drain, with the common pipe running to a condensate pump (see picture below). The Lennox Installation manual says both condensate drain lines MUST drain independently (i.e. one from the AC and a separate from the furnace). Contractor says, no my install is fine and "newer" version of the manual (which I can't find online) confirm this setup is ok.
Thoughts? Not sure why you can't tie this together.