Air Handler sweating bad, what can be done

[slicktoptt]

One of my air handlers is in the attic. It is mounted on it's side over a drain pan. With the summer heat (in Florida) I have had the a/c guys out 3 times because the drain pan fills up and the safety switch kills the outside unit. Yesterday I climbed up there and looked and noticed that the hadler is sweating and dripping into the pan right at the main duct connection.

What can/should be done to fix this or is it just hot attic air meeting with cold a/c air and nothing can be done.

At the moment I am waiting for a/c guy to come back out and run a drain from the pan to the drain for the handler so the pan will actually drain...not sure why they didn't do that to start with.

Thanks

 

[Charles (in GA)]

One of my air handlers is in the attic. It is mounted on it's side over a drain pan. With the summer heat (in Florida) I have had the a/c guys out 3 times because the drain pan fills up and the safety switch kills the outside unit. Yesterday I climbed up there and looked and noticed that the hadler is sweating and dripping into the pan right at the main duct connection.

Huh? Are you saying the air handler is not mounted right side up? How does its internal drain pan work? Is is made to be mounted in more than one way?

Is this house new to you? If so, did the home inspector not notice that drain pan wasn't really a drain pan because it didn't have a drain?

Charles

 

[wbrian63]

BTW - the box you're talking about, if it's what I think it is, is the evaporator. The "air handler" is a term used for the entire bundle of equipment which includes the air inlet, the blower/furnace unit, the evaporator and the outlet plenum where all the hoses are attached.

If the evaporator box is sweating, then either there's a massive air leak - which you should be able to feel, or the handler box isn't insulated, which it should have been from the factory. If the unit is newer, there should be an access port you can open to look inside at the airflow inlet side of the evaporator. Look inside to see if the box is insulated. It should be. If it's not, you need to get it insulated, pronto.

If you've got a cold air leak, the chilling of the outside metal will cause condensation, but usually, that's not enough to cause a drip pan to fill - the attic temps will usually evaporate moderate surface condensation before it can accumulate, and in FL you should have ample attic temps.

The overflow pan is a precautionary device - it is not designed to serve as the primary condensate drain from the evaporator coil - WHICH WILL produce GALLONS of condensate on a daily basis, especially in a hot humid environment like FL. It has a level switch that cuts off the outside AC when it gets full, because it should only fill up if the main drain pan (which is integral with the evaporator box) gets a hole, or the drain clogs.

Here in Houston, many houses, mine included have separate drain lines for the drip pan that exit the house in some visible location, usually around the main entrance or a kitchen window. If the homeowner sees water coming out of that pipe, they're supposed to know to call the A/C guy in...

If you're getting condensate into the pan, check the evaporator to see if the drain is clogged - from the inside. If it's not, you've got a "holey" pan, and I think the only solution there is a new evaporator...

EDIT - I just noticed your original post - "on it's side" - evaps should only be installed with the drain pan on the bottom. There are horizontal evaps and vertical evaps. Still, I suspect that you've either got a clogged drain from the evap pan, or the pan has a hole. Access to the pan isn't usually possible without a lot of deconstructive surgery, and then, the current hole is just a precursor to more holes in the future.

 

[slicktoptt]

The handler is is mounted horizontally. I assume they make units to be mounted in this configuration. Spoke to the ac guy and he said he spoke to Trane and they said they had some issues with the internal drain pan cracking and suggested replacing.

House is less than 2 yrs old

 

[wbrian63]

Hopefully this is a warranty issue. If the pan is split, there's your problem. Part of the work an A/C does is obviously cooling the air. Part of what makes the conditioned air more comfortable is dehumidification, which is also done by the evaporator. You definitely don't want a cold, humid house.

 

[bazar01]

The handler is is mounted horizontally. I assume they make units to be mounted in this configuration. Spoke to the ac guy and he said he spoke to Trane and they said they had some issues with the internal drain pan cracking and suggested replacing.

House is less than 2 yrs old

Also make sure the air handler is sloped a little towards the evaporator drain. You can shim the side opposite the drain side to make sure the condensate comes out of the drain connection.

 

[John Timmins]

I know what you're talking about. My condo has the compressor on the roof and the air handler on it's side in the attic crawl space. The drip pan fills up because the unit is sweating.

If you're using the top of the line air condition filters like Filtrete that is good for 4 months or the super allergy filters, stop using them. Get cheaper less efficient filters and change every 3-4 weeks instead.

Those expensive filters slow the air flow down too much. The conditioned air stays in the air handler longer and gets extra cold; that causes the unit to sweat and drip, filling the pan.

 

[bonneyman]

That's why I'm not a fan of attic installation. I prefer inside, closet locations - or at the least, in the garage. Makes for easier servicing and repair - and the condensate leaks don't ruin your ceiling! But, everybody wants houses with tons of closet space, so, builders stuff the units into the attic.
Most brands offer a multi-positional air handler. It can be installed vertically, or lay on either side. Builder's choose these because it gives them the most flexibility in the field. But, they are almost always set up for vertical mounting at the factory. (i.e. the condensate drain pan is in the position to work when vertical). If the installers didn't change the internal pan to horizontal layout when they installed it, that will cause leakage. The A/C guy will have to remove the coil cabinet cover and inspect inside to make sure the pan is in the right place. Many units also have shipping plates to hold the coil/pan securely during shipment. It must be removed before installation. If not, airflow is affected, and that could blow water where it shouldn't go. I've actually found this in the filed.
The metal pan under the air handler is an emergency catch pan only. Water should NEVER get in there. It's there to catch water if the primary pan fails or overflows. This pan is piped to a very noticeable location outside, so, if the homeowner ever sees water coming out, he knows he has a problem and shuts the A/C off till the serviceman can fix the problem. But I've seen alot of installations where the secondary (emergency) drain pan was used as the primary drain. Customers were told "water leaking out of that line is perfectly normal!". In a short time, that galvanized sheet metal secondary pan rusts out, and leaks into the ceiling. Maybe for days or weeks until you notice a smell or ceiling stain. By then, you've got structural sheetrock damage, and mold, if not a collapsed ceiling. I've seen this personally, too.
The unit being only 2 years old makes me think of these potential problems.

 

[burleymike]

It is also possible the evaporator coil is icing up, if the ice gets thick enough it will touch the air handler cabinet and create condensation on the exterior. I have seen a few systems do this if the evaporator is starved or not enough air moves over the coil.

Does the condensation form right away or after running for a while? If it takes some run time before it forms you might want to open the access door and see if the evaporator is a block of ice.