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Discussion Starter · #1 ·
Central Heating and Air located in attic

I have had water dripping out of the secondary condensate drain all over a window since I have owned the house (6 years) and I finally decided to do something about it. The first A/C guy I called hooked up a vacuum to the primary drain outside the house and a few drops came out. He said it was fixed and left. He told me that if that did not fix it then I must have a crack in my evaporator pan.

The second A/C guy came out and told me I need a p-trap in my primary condensate drain line and that if I could do it myself then I would save a lot of money. So, I added the p-trap. He was not wrong--there is a diagram on the side of the unit clearly showing that a p-trap should be installed. Unfortunately, although that was an issue, it was not THE issue.

I really did not want to pay for any more service calls, and since I had already borrowed a ladder to do the p-trap I decided to keep investigating.

Now I have the evaporator coil cover off and I can see quite a bit of standing water in the evaporator drain pan (not the overflow pan, which is dry). The water is below the level of the drain holes so it won't get out, and I have already made sure the drain pipes are clear.

After close examination, I noticed that the PVC pipe that was connected to the evaporator drain pan primary side had a very slight upward angle until it reached the first elbow fitting, then it started heading down hill again. So I cut the PVC pipe off at the other end and when I look inside I can see that there is rust color stains inside, but only half the length of the pipe. The water was headed down the pipe, but at a certain point the water level reached the same level as the secondary drain hole, which is only maybe 1/8" higher than the primary drain hole. At that point, the water diverted to the secondary drain because it is lower than the highest point in the primary pipe. So, that is part of the problem I think,

The other part of the problem is the standing water in the pan. I put a level on the evaporator case, and not only is the pan not tilted towards the drain as many sites say it should be, it is actually tilted slightly away from the drain.

So, here is my question(s): Should I tilt the entire unit, furnace, blower and all? Or is there a way to just tilt the evaporator pan, which is sandwiched between the furnace and blower? The whole unit is sitting on 4 or 5 foamy blocks that look like 4x4's that are about 2 - 1/2 feet long. Are there special shims available to adjust this? Do I just stick some wood blocks under the whole thing (between the foam blocks and the unit or between the floor and the foam blocks)?

The pictures are from before I started messing with stuff. Phone is acting up so the pics I tried to take today did not save.

Thanks for any feedback I get.


14,587 Posts
Easiest way is to tilt the whole cabinet sightly until it's draining correctly. It should only be a few degrees. Watch out for all the connections though.

It's possible to tilt the pan too, but it's usually very difficult.

Your biggest solution will be to fix the drain so it is sloping correctly, and completely befow the drain outlet. (Which looks like the problem is only a few inches worth of pipe.)

It is really hard to tell in your photo, but it looks like the coil is upstream of the blower. This removes the need for the trap. (drainage wise at least, is still recommended for efficiency) This means that lack of a trap should not have been causing a problem.

PS. You can also route the secondary drain to somewhere more reasonable.

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