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aero 06-21-2010 02:27 PM

I recently noticed that the supply plenum, I think that is what it's called, right off the air handler is sweating profusely. I have never seen this happen in the 4 years at my home. I have checked the filter and it was dry. The system otherwise is performing as well as ever. Any other ideas?

beenthere 06-21-2010 04:09 PM

Dirty coil.

aero 06-21-2010 04:15 PM

I thought if the coil was dirty it would freeze up and cut down on airflow.

beenthere 06-21-2010 04:18 PM

When it gets dirty enough it will.

aero 06-21-2010 10:13 PM

I cleaned the evaporator coil and ran the AC for roughly 1.5 hours to my set temp of 74 with an outdoor temp of 78. There was no condensation on the supply plenum. I think all is good but I am looking forward to seeing if this fix works when it is in the mid 90's tomorrow afternoon.

aero 06-22-2010 11:30 AM

It is 95 outside and the supply plenum and top of the air handler have a good amount of condensation. I am thinking of tearing the tape off where the plenum meets the air handler. It could very well be leaking. The tape existing is an HVAC grade duct tape and not the foil type tape. No mastic was used either. Am I on the right track and or should there be anything else that might be causing the condensation?

beenthere 06-22-2010 11:34 AM

The air handler should be insulated.

When you cleaned the coil. Did you clean both sides of it. Or just one. What did you use to clean it. Simple Green or some other cleaner?

Might want to check to see how clean the blower wheel is.

aero 06-22-2010 11:41 AM

I used a self rinsing foam on the underside of the coil in the upstream system. It appears the condensation is most prevalent where the plenum meets the top of the air handler and at another seam 16" up the plenum. I have not checked the blower at this point.

beenthere 06-22-2010 11:47 AM

If you feel air leaks. Then seal them up, as they will cause condensation.

aero 06-22-2010 04:06 PM

I resealed the plenum and still have condensation. I checked the blower which sits atop the evaporator coil and found condensation on the blower, the motor itself and the insulated walls inside. I can't really see if the blower is dirty. What is my next step?

NitroNate 06-22-2010 04:12 PM

this is a shot in the dark but what about standing water in the drain pan from a partially clogged drain. not sure if that could cause condensation like that or not.

beenthere 06-22-2010 05:44 PM

Was the blower sped changed recently, or this winter. Was a new motor installed this winter.

High velocity air through the coil, can pull the water out of the pan. It can also happen if the drain doesn't have a trap in it.

aero 06-26-2010 04:22 PM

Update. I had a tech come out and clean the blower wheel and install a brand new condensate line with a p trap. There was no water in the return plenum. In addition he checked the charge and notified me that it was at optimal temps and pressure. The system is working as good as ever. However, The top of the airhandler, supply plenum and blower are still showing condensation. The air speed is set to 1800 CFM on the 5 ton system as it always has been. The condensation problem started this summer.

beenthere 06-26-2010 05:40 PM

Known of us here know what optimum temps and pressures are. But many of us know what SH and SC is.
If he didn't check that, then no way to know if the charge is actually correct or not.

Did he measure the air temp in the plenum? If so, did he tell you, or write down what it was. And if so, what was it?

Post pics of the air handler, and of the supply plenum. And some pics of the return would help also.

aero 06-26-2010 06:01 PM

The SH and SC tests were done as I was there with the tech. The return box temp was 71 and the supply plenum was at 52

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