Drip pan under our attic A/C unit seems to be leaking. How are these things installed – drip pan on floor, then PT 2x4s nailed thru drip pan into floor, then A/C unit screwed or bolted to the PT 2x4s – is this right? If that’s right, then perhaps water is getting through the nails and/or any sealant failed… Is this a common on uncommon occurrence? House is about 10 years old with no previous problems of that sort. It doesn’t seem the plastic pan would otherwise fail. I’m guessing the whole thing needs to be ripped out and the drip pan replaced/reinstalled?
Any info/insight greatly appreciated!!
Replies
Are you sure it's the pan and not the drain line? Could the outlet or pipe be clogged? Could the pipe be cracked (frost)?
Lots of questions. No answers!
Al Mollitor, Sharon MA
Most hvac guys have drip pans fabbed at a sheet metal shop in that situation (stainless steel), and it should not have holes nailed through it that could be leak possibilities. Is your furnace a horizontal installation, being in the attic? If so, is your evaporator coil blowing moisture past the pan? or is condensate traveling back through the flange that the evaporator coil is attached to the furnace by?
And what the heck do you have the ac on this early for? It's still 50 here in indianapolis.
remodeler
Curious why they do not use drip pans made for washers. I have a large plastic drip pan made of plastic that my full-size washer sits in. I would think that 3/4" plywood nailed to attic floor joists then the pan liquid nailed (to death) to keep pan in place would be a better option then fabricatng a metal pan that will have seems.
BTW, how does a homeowner insure the drain pipe stays clear? In my neck of the woods I would expect condensation from the humid environment. But considering my shower I don't doubt for a minute bacteria and mold will find themselves growing in that drain pipe. I thought about Liquid Plumber once a year, but then again my nervousness for causing a bigger problem keeps me at bay.
Remember that the drip pan is supposed to stay dry, and is just for "in case" the primary drainage system fails.
So it looks like you have 2 problems
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When I lived in Az. I had an airhandling unit for the A/C and Heat Pump in the attic. The unit should have a condensation drain line. Under the unit I placed a pan which also had a 1/2" pvc pipe connected to it and also drained to the outside of the house along with the condensation line. Pitch is important on the lines and the lines need to be "shimmed" so that they don't sag (because of attic heat) between the joists.
Good Luck
MES
David, Are you are talking about the galvanized sheet metal pan or plastic pan under the air handler? It is an emergency pan to catch a leaking air handler case.
Your primary drain line may be blocked. You need to open the air handler and see if the condensate trough is draining and the drain line flowing well. Dirt and scum , especially from a poor filtration system, can block the drain.
The pan should not be nailed to the attic floor. No holes other than a drain line fitting.
Another source of moisture can be the "U" trap. It gets pretty cold when condensate is flowing, and condense moisture on the outside. Seen many that dripped into the insulation, because the trap is not over the pan.
Paul