Overflow Pan Fills On Central A/C

[PM5K]

It seems this started when the outside unit was replaced after having failed at about 13 years old. I believe it's a 5 ton unit. Shortly after that the overflow pan on the air handler started filling with water.

The drain line was cleaned twice, then the drain line was adjusted to make sure it had a good slope, then it was replaced with a different kind of PVC and added a trap which it did not have previously.

None of that worked so then a pump was added, but the overflow pan still fills.

We were first told that there might be damaged to the main pan, then were told that the outside unit is incompatible with the air handler, something about the expansion valve being the wrong type.

The thing is, we've replaced two other outside units, one a bit before and another at the same time as the one in question, all of the outside units are the same, and all of the air handlers are the same and we haven't had this problem with the other two units.

Thoughts or suggestions? We're looking to have someone else come in and look at it, but just wanted to see what the interwebs had to say about it.

[George2]

Question.........timeline of the home and the equipment? In other words......How many condensers? How many airhandlers? Dates of installation of each piece of equipment?

Were is the airhandler located? Filter size?

[PM5K]

My mistake, I just noticed this is for residential, the location in question is a commercial building.

Hopefully someone can move this to the correct location.

[beenthere]

Moved to AOP Commercial.

[PM5K]

Thanks. Hopefully I can get some thoughts on it.

[jim147]

Not really much info to go on. The pan fills up? Is this a known fact?

The drain has been worked on three times so let's just say that's not the problem for the moment.

Big question time. Has anyone looked at the coil? Is it leaning back? Is something floating in the pan blocking the drain? Is it just dirty? Or a few other things.

Sounds like you need a different tech to take a look at it.

jim

[PM5K]

The pan definitely fills up, since it's not connected to anything the float switch cuts the unit off and I have to use a shop vac to empty it to get it running again.

I don't know how easy it is to look at the coil, the guy working on it said the main pan could be leaking but he couldn't be sure because there's no way to see it, so I just assumed all of that would be difficult to get a good look at.

These are approximately 13 year old Ruud air handlers.

[wanttosee]

Is the inside pan filling up and overflowing into the other pan?

If the inside pan is overflowing, you probably have a draining issue.
If the inside pan is nearly empty, you probably have a leak in your pan.

No promises on what is wrong without seeing it in action. Is it upflow, horizontal or downfflow? What is the model number of the ah?

[XcelTech]

Sounds to me like the main pain is inside and no one will open it up to take a look.
I bet you got a system that is not level and no one will tell you that this is causing the unit to rust were the water is pooling and leaking cause the water never reaches the drain.
Most likely its not level cause your foundation shifted or because some one used the incorrect base which would be something like wood that deteriorates over time.

The only other thing I can think of is you have negative pressure and your AHU is sucking the water back into the unit.

[Txvman]

Thinking on this I wonder if the p-trap may not have been installed correctly. If the outlet side of the p-trap is higher than the inlet/ AHU pan it will will not drain properly.

[wanttosee]

Once the owner reports back about whether the pan is full or empty we can help him/her further the troubleshooting.