Thread: Height/configuration of primary condensate vent

What is the required height (length) of primary condensate vents? I have seen them simply as a tee with nothing in them to provide height, and seen some as much as 4". Also they usually seem to be taped over in Houston.

Some are not quite plumb, and angled to spill over into the overflow pan (seems like a decent idea), some are over the overflow pan. Too many different configurations. Looking for something in black and white that I can quote.

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Is this the clean out on the primary drain line of an attic/closet A/C unit? If so I call them out to be capped. I also recomend they add a cup of bleach monthly or so to keep the line clean.

Sal,

No where on the manufacture label of any bleach I've ever seen say it can be used on HVAC equipment or componets.

I would hesitate telling clients to put bleach into the condensate drain. For some reason the bleach were to back up into the equipment, it could cause possible hazards to the occupants and the equipment.

If anything, telling them to change their air filter on a regular basis is the best thing to prevent that algae from building up in the drain line.

JMHO

Rick

Here is a diagram I stole here from Lennox that has a pretty good diagram and explanation.
The IRC pretty well leaves it to the manufacturer and some of their information is sketchy at best.

Notice that Lennox requires a trap in both the primary and the secondary with the vent downstream of the trap, therefore no tape is needed to stop the airflow if the secondary trap is primed. I recommend using mineral oil or equivalent to stop the trap(s) from drying out.

I use to tell the clients to use bleach as well. I stopped for the reason Rick gave. Now I just tell them the line can get clogged and recommend strongly that they obtain an HVAC contract to keep their unit/system in good operating order.

The vent should be after the trap and there should be another vent like fitting with a cap on it just at the beginnging of or incorprated into the trap. I don't think there is a specified heght to the vent but I would think 3 to 4 inches would be in order. The vent over the pan sounds like a good idea and do see this from time to time. I have seen the vent a foot tall. I don't thnk it makes a difference as long as it is a few inches.

That diagram Jim just gave is what I usually see and also see the type with the clean out incorpoated into the beginning of it. I actuall put that diagram in my report if it is not plumbed like that.

Common sense would tell me to raise the vent higher than the outlet of the secondary drain at the pan so that when blockage occurs in the primary downstream of the vent, the overflow is pushed out of the secondary into the pan rather than the vent.
I don't think I have ever seen that in print.