Long story short, previous owner of my condo said the condensate overflowed into the ceiling. The building inspector suggested having an exterior drain pan installed. After move-in, I hired an HVAC company to install one after move in. System is a Carrier heat-pump.

I went up there today to inspect things and found a few things:

  1. The drain pan is directly tied into the secondary drain line

  2. The secondary drain line has no p trap

  3. The primary drain line has a very shallow p trap. Manual says the p trap should have a minimum of a 2" drop.

Here's the manual PDF: https://www.theacoutlet.com/documents/Installation-Guide-Bryant-FX4.pdf

I'm a little concerned since the current setup seems to be in direct conflict of the manual, but I'm just a homeowner, not a pro.

Also, in the event the primary condensate drain clogs, wouldn't the secondary drain begin to fill up the exterior drain pan without alerting me by draining out the visible exterior drain pipe? Should there be a check valve installed?

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1 Answer 1


The photo does not match the drawing,

The trap should be at-least 5 inches tall on the AC side and atleasr 2" less and 2" on the discharge side

The photo does not match the text,

Both outlets should have traps (as drawn in the picture).

From the trap to the discharge, the pipes should should never go upwards, only (vertically or sloping) downwards

The connection of the second outlet to the tray drain is allowed, but a trap is needed to prevent air leaks.

  • Thank you. Two follow up questions.. What's the downside of having the current setup / air leaks? Also, is there a common way to set up the PVC without glue to allow for easy condenser/evaporator servicing?
    – James
    Commented Jan 8 at 17:34
  • 1
    air leaks are going to harm AC efficiency - incorrecti drain piping may void your warranty. pipe unions (once installed) allow disconnecting and recconecting pipes without cutting and glueing
    – Jasen
    Commented Jan 9 at 8:26

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