Plumbers - Is home inspector wrong about condensate drain?

Question

A home inspector flagged a condensate drain line in the basement as improper. ("risk of sewer gas into air stream")

A 3/4 " PVC condensate drain line runs along the wall from the central air unit in the basement. At the end of the sloped run there is an elbow and a section of pipe which is sliped into a 2" dia. pvc pipe coming up 3 Ft. from the stack drain pipe. This 2"pipe has a trap on it before connecting to the stack so I see no hazzard of sewer gas.

How else would you run a condensate drain line?

What does plumbing code say?

Thanks for your help.

Answer 1

cant change from one size to another.. u gotta stay with the 3/4 all the way/.......

lic. gen. contractor

Answer 2

Is the 3/4" condensate drain from your A/C?  The reason the inspector is red flagging this is because the drain trap in the 2' could dry up when the A/C is off for a long period of time.

If you had another source of drainage going into the 2" pipe say the wash machine or a water softener drain the trap would never dry out.

Answer 3

As long as the 2" trap is properly vented then there should not be a problem.A 2 " trap should not be farther than 48" from a vertical vent pipe.After the trap the pipe should run horizontal with slight drop until it reaches vent connection.Otherwise the trap can siphon dry and smell.A properly vented trap will not siphon dry.A trap that drains only condensate can dry up and evaporate if water is not poured down on a regular basis.Once every 6 to 8 weeks should be enough to keep trap full.

Answer 4

In a normal coil installation, there is a trap installed immediately after the condensate exits the plenum. If you have a trap there, your inspector is full of "sewer gas", himself.

Answer 5

ask him if he would settle for a check valve $10 at lowes

Answer 6

the hazard is if the sewer back ups it can back up into your ac unit. the ac unit needs to be installed by either an air gap or just to the outside