Thread: Condensate Overflow Drain Pan

Hi,

I've recently started setting up my own Home Inspection business here in Maryland (where I am licensed). I've come across a situation with my own system above my second floor in my two story home. Two summers ago the drain from the unit got backed up and the drain pan below over-flowed and caused considerable damage to the ceiling in the Master Bathroom below. The service tech said that the galvanized drain pan under the unit should have been piped up with a secondary drain out to the soffit on the house to prevent the pan from over-flowing. I put this pipe in and tested it. That part worked great, however, I believe the galvanized pan has rusted through somewhere because the little bit of water left in the pan that did not drain out of the secondary drain pipe (i.e. because it is below the level of where the pipe comes into the side of the pan) is leaking through the bottom somewhere. Has anyone on this message user group experienced anything like this? What do I need to do to replace this galvanized pan with a plastic one and where can I get the plastic pans? I would imagine that I could temporarily suspend the unit from the rafters and raise up off the 2 x 4 's that the unit is currently setting on that are inside the galvanized pan long enough to replace the pan. I'm guessing I can raise it about an .125 to .250 inches in order to do this without disturbing much anything. Unless someone can give me a better solution or point me to a website for direction that will save me money in these tough economic times.

Please advise,

Steve

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If you suspect the auxiliary pan is leaking and it is not rusted much, maybe just some surface rust, I would leak check the pan by putting some water in the pan and looking for leaks.

Check each of the corners well as they not have been well made and may leak, also check where the drain connects to the pan as it may not be well sealed to the pan.

IF the auxiliary pan is leaking, do not replace it with a plastic pan, replace it with another galvanized pan.

If you can only raise the AHU 1/4" or less, you will likely need to have the AHU disconnected from the ducts, raised higher, then reconnected and resealed to the ducts in order to be able to properly replace the auxiliary pan. If the unit is setting IN the auxiliary pan, or is setting on wood blocks IN the auxiliary pan, then I would construct a frame which would mount to the attic floor and go over the AHU, hanging the AHU from that frame. You want your AHU to be free and clear of the auxiliary pan, being above it so the pan can collect the discharge from the secondary condensate drain pipe - there really should never be any water 'overflowing from the unit', not with a properly installed primary and secondary condensate drain line.

When I find a 2nd pan with corrosion, I recommend replacement of the pan. The pan has contained water causing the corrosion and will continue to corrode and at some point will not hold water. A terrific investment is to have a float switch or sensor installed in / on the pan that will shut off the unit when water is in the pan.

Originally Posted by Jerry Peck

If the auxiliary pan is leaking, do not replace it with a plastic pan, replace it with another galvanized pan.

Jerry.... why do you say do not replace it with a plastic pan?

Originally Posted by Dan Harris

Jerry.... why do you say do not replace it with a plastic pan?

Two reasons: 1) because the air handler is being supported by it; 2) because each of the few plastic pans I have seen all had cracks around where the drain connects and/or in the corners where the pan was formed around its form which made the material thinner/more susceptible to cracking.

A galvanized pan will last a l-o-n-g t-i-m-e, then replace it.

So it's actually a preference and not that it's not allowed. Galvanized over plastic, which I tend to agree on.

Plastic is good in a lot of situations but on some installations it don't quit cut the mustard.

Originally Posted by Wayne Carlisle

So it's actually a preference and not that it's not allowed.

Correct.

For the primary condensate pan IN the AHU at the evaporator coil, the choice is just the opposite: use plastic, not galvanized metal.

The reason is that the primary condensate pan basically 'always' has water in it, and we *know* that it will rust out, no question about it, so use a plastic pan there, besides, to change the primary condensate pan you have to pull the coil, which means evacuating the refrigerant and all the other related work.

When an AHU or furnace is installed properly 'above' the auxiliary pan, the auxiliary pan is easy to replace, no big deal.

Thanks to all for the feedback. One last question, if I buy another metal pan, should I get something to coat it with first to prevent leakage/future rust? The one I have now only lasted 10 years.


Please advise,

Steve

Originally Posted by Stephen Shockley

Thanks to all for the feedback. One last question, if I buy another metal pan, should I get something to coat it with first to prevent leakage/future rust? The one I have now only lasted 10 years.

Steve,

That's what the galvanized coating is for.

The problem is not that the pan did not last long, the problem is that water kept getting in the pan, which means the primary condensate drain line kept getting clogged (or maybe just the pan opening got clogged).

Keep the unit cleaned and the line free and clear, then water should not be getting into that pan like it was.

Also, I would install a shut off switch in the secondary condensate line to shut the unit off (but still allow condensate to flow past the shut off switch to the auxiliary drain pan). You could do that by installing a tee fitting and a regular shut off switch which is dead ended, secondary condensate flows past the shut off switch with some flowing into it, the unit shuts off, and the rest of the water flows past the shut of switch as needed.

The reason for shutting the unit off is to alert your that the unit needs servicing *now*.

With auxiliary condensate pans and no shut off switch, the units keep running ... and running ... and ... which means that the water in the auxiliary pan gets deeper ... and deeper ... and deeper ... and ... stays there for long periods - causing the pan to rust out.

Your problem is not that the pan only lasted 10 years, your problem is that it held water way too often. Correct what caused that and this new pan will last a long, long time.

Check your primary condensate line for proper flowing, slope (slope to be continuous and the same, any dips or bellies in it, or any high points in it, will cause it not to drain properly, which could lead to backing up - it should also be insulated all the way.