The evaporator coil for a friend's central air conditioning is leaking
condensate on the basement floor; however, the drain line is unobstructed
and also flowing water.
This is a Carrier unit of unknown vintage, and it was installed with the
access panel less than a foot from the basement wall, presumably because the
refrigerant connections are right below the panel, and it's a direct shot
from there to the outdoor unit. Whatever, it was a real pleasure taking the
panel off and getting it back on.
Could not see much with the access panel off because of the restricted view,
but I did see that the copper drain line was covered with water droplets.
The drain runs from the "front" of the evaporator housing to the back where
the drain hose connects. Thus the drain line runs through the inlet air
Noticed a small cover on one corner of the evaporator housing. Behind the
cover was a very short drain pipe with a rubber plug in it; from the factory
it appears. What is the purpose of this second drain connection? It
connects to the same reservoir as the other drain, but a fair amount of
water came out of it when I took the plug out.
I'm guessing that the condensate tray could have a leak in it, but I don't
see any easy way of accessing it short of cutting a hole in the housing. I
don't know what these trays are made of or if they are are prone to rusting
Alternatively, I'm wondering if the uninsulated drain line, which has cold
condensate flowing through it, is condensing the humidity of the incoming
air and that is what is leaking out of the nearby joint between the
evaporator housing and the furnace housing that it's mounted on. That's
where the water is showing up when the unit is operating. The existing
drain line has a trap in it so there is no air flow through it.
My first thought is to put insulation on the drain pipe inside the
evaporator housing, but it will be exceptionally difficult to reach. My
second thought is to plug the present drain and install the hose on the
presently unused drain so that there will be no flow in the uninsulated
section and no condensation on its outside surface.
What do you suggest?
You may have a condensate pan that has a leak maybe due to rusting.
Sometimes they can be replaced but a new evaporator coil may be needed.
The unwrapped drain line maybe the problem but if it is part of the problem
then it most likely it would have leaked from the beginning when the system
Some units have a second backup drain pipe in case the first one gets
blocked. The fact that a lot of water ran out when you opened it
suggests that the actual drain line is at least partially blocked and
not flowing freely, or there would be very little water to run out.
On Mon, 11 Aug 2008 21:44:36 -0400, "Silver Surfer"
I had water on the floor, also with a Carrier, from 1975.
FWIW, my outside unit is directly opposite the inside unit.
Everything worked fine for the first 5 or 10 years I lived here, plus
I suppose the 4 years the other guy did.
Then it started going on the floor and not into the sump.
I took off the plastic drain pipe, and blew through it with my lungs.
Twenty feet but it didn't seem clogged. Still I ran faucet water
through it to flush it out, and the water came out full blast. Put it
back together and it didn't work any better.
I cut open the plenum to look inside. Not a lot of water, but I
probably hadn't been running the AC for days or weeks before that.
Everythign looked ok inside.
I may have done other thigns but this is what worked. The plastic
pipe came out an inch, then turned down for 3 or 4 inches, then
sideways to the wall a couple feet**, then down to the floor 4 feet,
then along the wall 6 feet, then sideways to the sump 2 feet, and down
**This piece was horizontal, not uphill.
All I did was rearrange the pipes so instead of going down 3 inches,
it goes down 2 feet before it turns sideways, same distance to the
wallk and then down 2 more feet or so to make 4 feet total.
Now it works fine. It's hard enough to understand why it works
better now than it did, but even harder to understand why it worked
fine for 15 years and then didnt' work anymore.
I"m going to post and send you a copy. If the comcast people are
reading, Hi, guys!
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