AC condensate to sink drain

Would anybody say anything about this? The ‘code’ says condensate must discharge to an “approved” place but doesn’t get specific.

If the drain clogs the water will back up into the condensate line

Wouldn’t it overflow the sink bowl first?

It depends on how high the other end of the condensate line is. If you block that p trap it will back up through that line until it can spill over the sink bowl level

HVAC unit was in the attic.

prolly good in this case.

No air gap,

The open sink drain is, no? Just like a dishwasher connection under a sink.

The proper/ideal way would be to use a p-trap and air gap/barb combo, but since it’s not potable water, it would be a bit of “overkill”, IMO.
This fitting is one (or similiar to) I’ve used/recommend for condensate and softener drains tied directly and improperly into DWV systems.


Agreed this is what I would like to see, I also see a lot of condensate lines draining at the washing machine drain. Especially in townhomes.

Code does say otherwise…

The purpose of an air gap is to prevent siphoning of water back into a potable water system.

That does not apply here.

Is it right? No

Is it much of a problem? I’m not seeing it but if given a reason I will change my mind.:wink:

Gas furnace?

Actually the code doesn’t say much at all about the primary condensate drain.

May drain to indirect receptor (lav, tailpiece, tub overflow) UMC 310.5

No direct connection to wast or vent pipe: UMC 310.1 IRC 1411.3

So this connection is fine.

“IRC M1411.3 Condensate disposal. Condensate from all cooling
coils or evaporators shall be conveyed from the drain pan outlet
to an approved place of disposal.
Such piping shall maintain
a minimum horizontal slope in the direction of discharge
of not less than 1/8 unit vertical in 12 units horizontal (1-percent
slope). Condensate shall not discharge into a street, alley
or other areas where it would cause a nuisance.”

Where does it say no direct connect to waste or vent pipe?

I don’t look codes up but for the past 51 years you have never been able to connect a condensate drain to a vent stack unless the trap is a wet trap which means there must be a liquid seal in the trap 365. A 80 % furnaces makes no condensate thus the trap becomes a dry trap in the heat season. Its a matter of dry trap VS wet trap the pic in the OP would be a adequate means of disposal because the trap is considered a wet trap below the lavatory

That’s how I justified it. The trap was always wet and there was no chance of sucking nasty air back into the system. This was a townhome. Every unit in the place was likely the same and the drainage was obviously “approved” by the AHJ. Could not justify saying this one particular unit needed service without a good cause.