Some one please explain

[mcotten]

Found a dip in the condensation line for a new furance. Why would an installer put a dip in the line?
Any help would be great.

[Jeffrey R. Pope]

Are you talking about a trap?

Traps are required in most jurisdictions and are commonly made "on-site" by heating up the PVC.

[Jay Moge]

Mike, that is a trap as Jeff said. so long as the top of the lowest part of the pipe is lower than the lowest part of the higher pipe on either side, it will act as a trap. i've also seen a series of fitting to do the same thing. think inline and go; pipe, 45 going down, 1 or 2 inches of pipe, 45 going strait, the 45 going up then pipe then 45 going strait again. a little more costly the heating and bending, but still effective.

[Dean Call]

That type is called a "running trap" and it's a pre bent - glue on deal that you buy along with the fittings.

Most condensate drain lines are "indirect waste" (not connected directly to the sewer) and therefore do not require a trap at all.
The exception to that is IF the condensate drain is on the negative pressure side of the evaporator coil, the suction from the blower motor can suck water back up the line and make a mess if not trapped.

Looks like that one is on the positive pressure side of an "A" coil, how did the end of the pipe terminate?

[David A. Andersen]

It also keeps unconditioned air from being drawn in from the outdoors and conditioned air being blown out.

This condition may put the house in a negative pressure and cause undesirable stuff like pulling in Radon and Molde spores from the crawlspace or unfinished basement.

[mcotten]

Thank you guys. This was the first I have seen in 2 years.