A/C condensate line

I always call-out a A/C condensate line that drain directly into the plumbing system (no air gap) even if a p-trap in the line is provided, over here that p-trap will dry out during the winter, am I calling this right ? would the same apply to furnace condensate line

All modern installations in my area will drain to the tailpiece of a sink drain or laundry drain. What makes you think this is improper?

I don’t think I’ve ever seen a furnace that produces condensation. . .

I am in north Ontario A/C are 95% install on force air furnace and if the condensate line is install direct to the sewer pipe it could draw sewer gas .In this area high efficiency furnace have condensation line that goes to a drain of some kind.


We have the same, Jeannot.

Typically the condensate drains to a condensate pump and that pumps it up and into an airgapped drain line.


If the condensate line is plumbed to a sink tail piece I do not call it out as the sink will most likely have water in the trap. Same if it is plumbed to the washer drain. Now if it is plumbed to a trap that you think will go dry, by all means call it out.

If it is plumbed into a waste vent I always call those out.

Thanks for your comment, that’s what I thought. I wonder why HVAC technicians keep installing them directly in the sewer line

Because they have not been properly trained or just don’t care just because one works at a HVAC company does not necessarily make one a Tech

Jeff you lost me don’t they have 95% furnaces in CA???

Bk **always **is a very broad statement what if the unit is installed within the attic and is a 95% furnace with a trap between the unit and a vent stack what is your call on that set up;-)

I call a waste vent, a vent. And a drain a drain. Usually it is an easy call because HVAC guys make lousy plumbers.

and plumbers are always worse as HVAC guys, well maybe not in all cases, there is **always **an exception :wink:

I had to think about this a bit Charley. :slight_smile:

If I am not mistaken a 95% efficient furnace the condensate comes from the flue exhaust. Which would mean that if the trap ran dry sewer would not enter the attic or the furnace air stream, I would be ok with it. :smiley:

I have run across another’s one today, a/c had a p-trap in the line but was connected directly to sewer line. This summer here in northern Ontario a/c might have run two days that p-trap will spent most of the year dry. Worst the H.R.V. condensate line was connected directly no p-trap.

Me too local AHJ allows it also as long as the trap at the unit is wet

You did good just keep calling them out trap must be wet 365 if not it is wrong no ifs ands or buts

Around here the reason, for air handlers installed in the attics, is that the lines have little room for much slope and the traps get plugged up with algae or trash during the summer. I’m not defending the practice, however.

This 6 year old thread was brought to my attention recently, where I made an obvious mistake in my post…

I can’t say what I was thinking at the time, but high-efficiency furnaces do indeed produce condensation and I have been inspecting them for years.

Thanks for the heads-up Dave.

KW was not around back then or he would have set you straight:mrgreen::stuck_out_tongue:

No doubt :wink:

Well, we have a 1 Year break from him and then he will be back completely edumacated to tell us all he has learned in a year. ;):slight_smile: