Condensate drain line in plumbing vent pipe

HVAC in attic with condensate pump line discharging into plumbing vent pipe. Is this OK?


Is there a trap of some sort? That would be important if it is the cooling coil condensate drain. Possibility of circulating sewer gases in conditioned air if there is no trap to prevent that. Otherwise it should be OK.
Manufacturer’s install should be consulted, download the pdf using the model number.

If the unit is in a attic why is there a pump. You not giving much info for us to work with here. Let me explain what we do in Okla and you can decide from there.

If discharging into a plumbing vent in the attic there must be a wet trap as defined by water discharge sufficient to maintain a seal on the trap. If the furnace is a 80% furnace it makes no condensate thus the trap could go dry when in the heating mode and could allow sewer gas into the air stream and into the home. The trap would only be sealed while operating in the cooling mode

In your pic if indeed a pump is used the pump normally is considered a trap

Thanks guys,
Yes there are condensate pumps. Charley, won’t the pump basins dry out in the winter as well and therefore allow septic gases into the attic at least?

You can’t drill or tap a hole in a DWV line.

Yes they will

I write them up here , Another thing that is acceptable in these parts . Sometimes you just to say hmmmmmm lol


The condensate does not “dry up” in a condensate pump system…

The tank can dry (or be emptied and cleaned at the end of the season (yea, right everyone does PM’s)), but there is check valve in the hose and it will not drain.

But anyway, it must be a wet trap if connected to the sewer.

Never seen a check valve in a little giant pump discharge line

Replacement Check Valve page (3).