Condensate back pressure?

[indoctrin8ed]

I installed my own cased horizontal evaporator, which is adjacent to my furnace in a closet in my furnished basement. I first put in a p-trap that drops 6 inches, then rises 3 inches, then runs about 2 feet horizontally with a 2" slope into a "Little Giant" condensate pump. I used 3/4" PVC tubing. Total distance is less than 3 feet. The pump then has about 6 feet of tubing to the outside. Then P-trap is "primed".

The problem is: Condensation will not drain out of the evaporator when the blower is running. The pan overflows and then, of course, leaks.

I made a "workaround", (eg, a hack), and I want to know if you guys think this is ok or will cause problems down the road, or maybe I have another problem that I should be addressing.

I kept the p-trap as it were, but replaced the PVC elbow with a PVC "Tee" where it attaches to the drain fitting on the side of the evaporator. The "Tee" allows drainage to flow down into the P-trap as before, but I left the other end of the Tee open and facing UP. This allows some air to flow out, and seems to release back pressure that I assume was preventing condensation water from flowing out via gravity.

I realize this leaks some air, but it's minimal, and is leaking air into a living space of my home which needs to be air conditioned anyway, so that's doesn't concern me as a loss.

Everything works great now, but I’m wondering why my p-trap can't work like everyone else’s…? Am I ok running this way?

Many thanks.

[tinknocker service tech]

remove the trap or put a tee in place of the first 90 with a vent before the trap

on a positive pressure coil meaning on top of a furnace if you put a trap in with out a vent the air will blow in hit the trap and blow back to the coil holding the water in the tray till the blower shuts off then gushes out

trap isnt needed on this aplacation IMO

if you want it fine then run a straight piece of pipe off the coil then a tee up and down trap in the bottom of the tee and a short piece of pipr out the top

you can then see the air blowing out and the water falling into the trap and out

[indoctrin8ed]

Thanks for the reply.

Yes - I have a positive pressure coil that's doing just what you said.

I installed exactly as you said (Tee acting as a vent, replacing the first 90) but still with the trap, and by what you said, it seems I can do without the trap, especially since there is only 2 feet of total tubing once the trap is out. Plus, with the open Tee as a vent, it makes it super easy to clean the tubing.

So I'll remove the trap, keep the Tee and vent.

Thanks again!

[t527ed]

might want to check static pressure on duct system.

[morrmech]

The tee always goes after the trap.That way air wont suck through the tee and cause the water not to drain out of the pan. The trap of water stops the air flow and lets the water drain. Check coil pitch, drain knock outs,primary virsus secondary.