Vent Stack with Condensate Lines

I’ve researched the threads and found only one reference to substantiate not having condensate lines piped directly into vertical plumbing vent stacks.

It is in IRC 2003 P3101.3 Use Limitations. The plumbing vent system shall not be utlilized for purposes other than the venting of the plumbing system.

Is this improper? There are no traps and the units are located in the attic.

Can anyone support this with an appropriate code reference?


Proper photo attached this time.

AC lines2.JPG

Is this the auxiliary and secondary drain ?

These are Primary Condensate Lines.


Whether it’s allowed or not, those types of connections are prohibited. Without the proper fittings, it doesn’t matter what the code says - it’s wrong.

**P3005.1 Drainage fittings and connections. **Changes in direction in drainage piping shall be made by the appropriate use of sanitary tees, wyes, sweeps, bends or by a combination of these drainage fittings in accordance with Table P3005.1.

Good stuff Jeff. No thread drift with your posts. You’re the best Left Coast inspector around. :smiley: Hope you have a great 4th Quarter!

Is this the best area to deal with this? This is vent piping is it not? I think you stated it best with your first post Hank.

I write soft water brine drains up all the time as being wrong.

I thought it was since we were talking about plumbing vent stacks. When I think of venting in HVAC, I think about flue vents for gas-fired appliance.

Hank, I think you nailed it with your interpretation of the code in your first post.
I was refferring to Jeff’s reply about drain piping, I do not think the drain piping part of the code Jeff mentioned is appropriate for the question you asked. The condensate is tied into vent piping and it is wrong.

This could arguably be considered a wet-vent with this type of application, which is why appropriate fittings would be required.

Condensate drain lines are commonly tied to vents and/or drains.

I understand what you are saying Jeff but do not see the section of code to support this.??

I write up every condensate drain line I observe piped into a vent or drain line that does not have a air gap and I state the reason for this as being not a code violation as we are not code inspectors but simply it allows sewer gas into the air stream of the furnace even when there is a P-trap installed because this P-trap will and does remain dry during the heating season unless the furnace is a high efficiency and producing its own condensate.

As you should.

This is an indirect waste line which requires an air-gap and a trap.

Could be a "combination vent and waste system."

Aside from that, and what has been mentioned by others:

Looks like a nice job of compromising the integrity of the truss. I guess they made up for it with that “approved” duct tape, metal lath or plumber’s strap wrapped around the pipe. I’m not sure if the truss is supporting the pipe or the pipe is supporting the truss! By the way, is that cotton candy all over the place?

Off the top of my head:

Drilling a hole in the pipe to make an access would fall under the same heading as a saddle tap, which is prohibited by code.

Joints in plastic piping are to be made with approved fittings by solvent cementing, elastometric gaskets or other approved manufactured system.

Jeff, are you saying it needs both? It is common practice here and has been for quite a while to route the a/c condensate drain line to the fixture side of a lavatory drain. No air gap but it is installed before the p-trap for that lavatory.

Technically, all indirect waste piping requires both. I rarely see an air-gap.

All indirect waste piping shall discharge through an air gap or air break into a waste receptor or standpipe.

I can’t find an IRC reference to support this, but here are the CPC/UPC references. . .

California Plumbing Code

815.1 Condensate Disposal. If discharged into the drainage system equipment shall drain by means of an indirect waste pipe.

815.3 Point of Discharge. Air-conditioning condensate waste pipes shall connect indirectly to the drainage system through an airgap or airbreak to:

815.3.1 A properly trapped receptor; or

815.3.2 Other points of discharge acceptable to the Administrative Authority, including dry wells, leach pits, the tailpiece of plumbing fixtures, etc.

I see that here also Michael

. And sometimes I see this.:slight_smile:

And I have seen package systems draining into a roof vent I might not have called out.