The P-trap usually keeps any cold air from blowing out the condensate line because the trap is full of water and the air pressure isn't high enough to blow the water out

Don

Thanks for replies. My terminology may not be exactly correct, but here's how things unfolded. There was no water in the line connected to the T-tube. I'm assuming that is the primary condensate line. Water was dripping like crazy from the other tube sticking out (I'll assume that's the secondary condensate line)and into the pan. I poured water into the T-tube and it flowed freely downstream, so I ran a wire up the other direction and also blew it out with compressed air, then water trickled down that tube and the secondary tube went dry. It's the secondary tube that's blowing out cold air.

Without the P-trap, my air handler sucks air from the condensate drain. It doesn't blow air from the drain, as the drain is on the suction side of the blower.

I once had to cut the PVC drain to re-route it (removed the p-trap), and left a bucket temporarily under the cut piece. Once the a/c and air handler turned off, water gushed from the cut drain pipe. The condensate was able to overcome the suction of the air handler after it filled the drain pan and built up enough head pressure. With a p-trap, condensate water flows easily into the drain. I never realized how important the p-trap is to drain flow until after I temporarily removed it.

"It doesn't blow air from the drain, as the drain is on the suction side of the blower."

The vast majority of systems have the evaporator coil after the fan, and thus at a higher pressure.
A squirrel cage blower is better at pushing than pulling.

Well the tube with an open end coming out of my unit (which is the tube that was dripping before I cleaned out the one with the T-tube)is the one blowing cold air. But I mean it's BLOWING cold air! Could it be that in my unit it tube is on the wrong side of the fan?

"The vast majority of systems have the evaporator coil after the fan, and thus at a higher pressure."

- I guess I'm the odd man out with a heat pump and back-up electric strips. From the bottom up: it's the A-coil, then the blower, then the electric strips. Air is drawn thru the A-coil at the bottom and blown out the top of the air handler.

OK... this has me really confused.

On our system, there is a secondary line for the overflow pan.

The is also a primary condensate line, with a p-trap, that feeds into the sink in the bathroom below. On that line, one foot out where it leaves the coil box, it has an upside down T that is open, and cold air blows out of it. What is that for? My HVAC guy said it's OK to cover it with tape -- I just use it in heating season to pour a bleach-water mixture in so that the p-trap stays full.

Can I cover up a similar T in the other system (it blows cold air out) that uses an external pump (with overflow safety) to move the condensate out to the drain?

If there is a pipe stub get a cap and push it on.
If the stub was omitted you could glue in a stub (you only need about 2-4 inches of pipe) and then push a cap on.
The pressure is so low (less than a few inches of water) the cap will not pop off if you push it on firmly.

Well I thought of capping it off, but that would defeat its purpose in the event the primary condensate tube became clogged again.

Thanks brickeyee.

cdsol... Not in my case -- there is already a secondary. This is a T stubbed up on the primary line.

"Well I thought of capping it off, but that would defeat its purpose in the event the primary condensate tube became clogged again"

What?
If the line gets clogged the pan will spill on the floor, the same as the tube.
If the unit is over finished space that could be damaged a secondary pan and drain is required.

The T is to clear the line, not act as an overflow.

Brickeye - thanks for your reply.

I think you misunderstood. I didn't mean capping off the stub. I meant capping off the secondary tube (the one without the T and drips condensation into the pan if the one with the T fails). That's the one blowing cold air, not the one with the T. Of course I won't cap it off 'cause it wouldn't drain if it had to.

I'm simply trying to understand whether I need to be concerned because that secondary drain tube is blowing cold air into the attic.

Carl

I would not want any conditioned air blowing (wasting) into the attic.

The secondary pan is not usually even be in the air handler.
It is a pan under the air handler with a separate drain.
They are not usually trapped since they are not under any air pressure.
What kind of equipment is this?

How 'bout if I email'd you guys a digital pic? Is there a way to include an image with a post? Otherwide I'd have to send it to each of you individually.

/Carl

I much prefer to upload my FULL sized photos to Photobucket.com, (it's Free!)
then just copy the "HTML Tag" Just Below each photo on your photobucket
page. Next paste that "Tag" into the message (right here) in the body
of the post on GardenWeb.
You can also do multiple Pic's in the same post. Simple and
no resizing and you can see your pictures when you preview the
post before you click the "submit message" button.

HTH
Chris
{{gwi:317886}}

Uhhh, hey, is that like some kind of picture of the rolling stones? :-)

Seeds Man! Seeds;-)

Those look like kidney stones. Ouch, that musta hurt.

If i cap off the pipe stub i get a very annoying sound in my bathroom sink, is this supposed to do this

I have the same issue with cold air blowing out of my condensation line I have a Goodman outdoor AC/Furnace unit. Any help on the matter would be greatly appreciated