One of our air-conditioners is supposed to drip condensate into a pump, which is then supposed to push it outside. Nothing extraordinary, and it mostly works...

Because not all water drops into the pump, there is a larger secondary drip pan underneath the AC to capture it. That secondary drip pan fills up -- and nothing drains it...

Because the pump itself sits in this secondary pan, I'm wondering, if I should simply make a few holes in the pump's own little basin -- to make it work on all the water, regardless of whether it makes it inside the pump, or ends up in the drip pan...

Will that work?

  • 1
    Won’t that result in your secondary pan staying wet all the time. The amount of water needed to trigger the float in the pump would be the whole pan full. Fix the tube entering the pump so it doesn’t drip into secondary pan
    – Kris
    Oct 10 at 14:17
  • I'm perfectly fine with the secondary pan staying wet -- it is located on the ground in crawl space. My goal is to prevent it from overflowing -- into that ground, which then sips through the brick wall :(
    – Mikhail T.
    Oct 12 at 19:16
  • 1
    Check to see how high the water gets inside the pump before it cycles on. That is how high the water in your pan will be before the pump kicks on. Can you add a picture or two to your question?
    – Kris
    Oct 12 at 19:48

Borrowing from Z4-tier's opening, it may depend on the design of the condensate pump. If the plastic case of the pump has holes, then the water level in the plastic case will only get to the height of the water in the drip pan, not the water level it may have had before in the unmodified plastic case. The water level may not be enough for the pump to get a suction on and then the pump won't pump anymore. The level of water required to activate the pump may never be reached, and the pump may never turn on again, leading to overflowing of the drip pan.

It may be better to have someone see if the water that flows into the drip pan can be captured and diverted into the condensate pump. Maybe there is an unexpected leak somewhere. (My furnace AC had a condensate pump but no drip pan and we never needed a drip pan.)


It depends on the design of the AC. Some units use the condensate (and accumulated rain water) to help cool the condenser. Window AC's often work like this, which is why they don't have drain holes in the bottom. If the fan is mounted in a way that lets the fins dip into the pan, it's probably to allow the fan to sling the water around, and you should leave it alone. If there is absolutely no chance that the water is doing anything useful for the system (like if the pan is an aftermarket add-on and not something that came with the AC), then it's probably OK to add drainage.

If you do decide to add holes, make sure to cut power first and be aware of what is on the other side of the spots where you drill. Breaking a refrigerant line is a very expensive mistake (and so is getting electrocuted, but at least then you don't have to see the repair bill).

  • I'm not planning to drill the AC. I'm planning to drill the bottom part of the condensate pump -- a rectangular plastic vessel at the bottom of the device.
    – Mikhail T.
    Oct 9 at 5:01
  • if it's a completely separate overflow pan, then it shouldn't be a problem. I'd just caution that whoever installed it probably did it for a reason. Maybe the local building inspector wants it like that, or the manufacturer requires it as part of the warranty terms. It might help if you posted a couple of pictures.
    – Z4-tier
    Oct 9 at 5:08
  • I think, the original installer didn't expect any water to miss the pump. But the AC is cold (on the outside), which causes condensate to form on it everywhere -- dripping down.
    – Mikhail T.
    Oct 9 at 22:45

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