Stubborn Condensate Leak on A-coil


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Old 08-18-12, 06:38 AM
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Stubborn Condensate Leak on A-coil

Working on an improperly draining A coil in an American Standard downflow fan coil unit.

Maintenance guy allowed to filter to clog a month ago and some initial dust still could be slightly clogging the coil.

R-22 pressures have been checked. The pvc condensate drain is clear.

This coil has been cleaned twice with green Diversitech light foaming concentrate cleaner from Michel.

Condensate leak stopped and then started leaking again after a month.

Though we've used it for years, have others found a better or more effective coil cleaner than the green Diversitech?

Fan is variable speed (non adjustable) and air flow does not seem to be an issue.

Curious if Pros reading this forum know of Anything else besides a partly clogged coil that could suddenly cause this 8 yr old system to develop a condensate leak - other that what we've mentioned above?

Suggestions welcome.
 
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Old 08-18-12, 09:00 AM
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Where does the condensation come from? Like near the pvc drain or in the back?
 
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Old 08-18-12, 11:31 AM
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could be a shield needs installed. Is there a drain trap installed?
 
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Old 08-18-12, 07:55 PM
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There is a drain trap and it is clear as is the full drain line.

Not sure where the shield might go. This is an 8 yr old A/S unit which has worked perfectly until now. Wonder if I can get a cut sheet on the coil which might show some shielding?

There was some rusty sediment in the condensation collection areas initially, but not now. It is possible that some very small metal shield of some kind corroded and fell off. That would be hard to determine, without seeing a new one to compare.

The only factor that discounts the possible shield theory is that for 30 days after coil cleaning it operated perfectly.

During normal operation it is not possible to see the precise source of the leak as it's a downflow unit with the a-coil. Even if you used a temp plexiglass door you still cant see the underside of the coil, while it is operating.

The water drips down on the blower housing and then leaks down through the floor.
 
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Old 08-25-12, 09:34 AM
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I appreciate the previous helpful suggestions!

This was with the 8 year old 2 ton A/S counter flow fcu in cooling mode

The plot thickens....

The coil has been cleaned again and the underside has been blow out carefully with compressed air. Without effect.

Techs have worked on this unit three times and have no clue.

Installing plexiglass instead of the lower door cover, we see the leaks! It's not the drain pans. The condensate drips are coming from the underside of the coil (it's downflow with the coil on top) The drips are coming from one or two single rows representing the copper tubing running horizontally in the coil about 1/4 of the way from the top of the A. (Maybe 4" down from the top)

There are some condensation drips from the opposite side of the coil at about the same height....but much more on one side than the opposing side.

As mentioned earlier the R-22 pressures were checked recently and may need to be checked again. Does this sound like a refrigerant issue?

We've yet to experiment with the variable speed motor speeds. Not sure if more or less fan speed might be helpful.
 
 

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