AC condensate drain

[Jaeyoung Lee]

The location of the vent on the primary drain is okay? I heard it should be downstream of the P- trap.

Is the installation of overflow shutoff switch or water sensor required by code? I heard from my HVAC guy that it is not required and it can be malfunction causing shutoff the system for no reason.

[Jim Robinson]

Here is some good information for you:

http://www.ashireporter.org/HomeInspection/Articles/Let-s-Concentrate-on-Condensate/1648

If you think of it as a clean out riser instead of a vent, it will make more sense. It does not function as a vent, and can be capped off if desired, as long as the cap is removable.

[Jerry Peck]

In addition to capping that open pipe to the primary condensate drain trap, the secondary drain also requires a trap.

[Jaeyoung Lee]

Here is some good information for you:

http://www.ashireporter.org/HomeInspection/Articles/Let-s-Concentrate-on-Condensate/1648

If you think of it as a clean out riser instead of a vent, it will make more sense. It does not function as a vent, and can be capped off if desired, as long as the cap is removable.

Thanks for the useful link. I still have a few more questions to make sure:
1) Are P-traps required by code for both primary and secondary drain lines? If yes, why?
2) Are trap vents also required? If yes, at downstream or upstream, and why?
3) Is the primary drain line to be insulated? If yes, why?
4) Float shutoff switch or water sensor is not required by code. Right?

[Jerry Peck]

Thanks for the useful link. I still have a few more questions to make sure:
1) Are P-traps required by code for both primary and secondary drain lines? If yes, why?
2) Are trap vents also required? If yes, at downstream or upstream, and why?
3) Is the primary drain line to be insulated? If yes, why?
4) Float shutoff switch or water sensor is not required by code. Right?

Keeping the answers short and simple:
1) Yes. Because the manufacturer's installation installation instructions require traps (for the "why", go here: http://0323c7c.netsolhost.com/docs/Trane_-_Trapping_Design_Flaws%5B1%5D.pdf ).
2) No. However, if installed, then downstream of the trap (all vents are downstream of the traps connected to the vent).
3) Yes. Because condensate is cold water (quite cold), and cold water in a pipe cools the pipe, which causes condensation to form on the outside of the pipe, and that condensation drips off onto ceilings, etc, creating issues caused by water (staining being the least of the water issue).
4) No ... but ... those are some of the options for the auxiliary condensate drain pan in stead of a drain line (water sensor is not an option, unless the water sensor is listed for shutting the unit off and is not just a water sensor for an alarm for the occupants to know that there is a problem - the intent is to provide an auxiliary pan for when the primary drain/primary drain pan clogs and overflows, catching that water, and then draining that water out to where the occupants will see it and know there is a problem... or ... using a float switch to shut the system down ... so the occupants will know there is a problem).

Okay, so answer 4) was not "short", and maybe not "simple" either, but it was as short and simple as I could make it and have it make sense.