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Where the water goes, and when you have to drain it
Updated
Cooling pulls water out of the air. Most portable ACs blow most of it out the exhaust hose as vapor, so you rarely empty anything. In humid weather some water builds up in a tray, and you either drain it by hand or run a hose to a floor drain.
The three ways water leaves
- Auto evaporation. Midea's FAQ says water collects in an internal pan and is sent out the exhaust hose as vapor. Whynter describes the same thing. Both say you will still need to drain now and then in humid weather.
- Manual drain. Midea says to set a pan behind the unit and unscrew the drain cap, and warns that water pours out right away. Keep towels nearby. Tip the unit back slightly to get the last of it.
- Continuous drain. A hose on the drain port runs to a floor drain. Whynter says the hose must run downhill the whole way and not be kinked or raised, or the water will not flow.
The picks and their drain options
| Model | What the listing says |
|---|---|
| Whynter ARC-14S | Patented auto drain that the maker says exhausts all condensate in most environments |
| Whynter ARC-122DS | Same auto drain claim, with upper gravity and lower drain ports for continuous use |
| Midea Duo 12,000 BTU | Drain hose included |
| Frigidaire FHPC082AC1 | Continuous drain capable |
| BLACK+DECKER BPACT14WT and BPACT10WT | Water drain parts listed in the kit contents |
| Midea 8,500 BTU | Dehumidify mode listed. Drain details were not in the part we read |
Know the full tray warning
When the tray fills, the unit stops cooling and shows a code. On Midea units, the FAQ lists P1 as "bottom tray is full" and says to connect the drain hose and drain the water. If a unit suddenly stops cooling on a sticky day, check for this before you call for service.
Leaks
Water on the floor usually means a drain cap that is loose, a tray that overflowed, or a continuous drain hose that runs uphill somewhere. Owners of the Whynter ARC-122DS mention leaking in the review summary we read. Set a towel or a low tray under a new unit for the first humid week.
Drain parts can fail too
In December 2021 the CPSC announced a recall of about 33,570 Royal Sovereign and Royal Centurian portable air conditioners. The CPSC said a faulty drain motor could ignite the plastic case, a fire and burn hazard, and one death was reported. None of the picks here are part of that recall. The lesson is general: register your unit so the maker can reach you, and check the CPSC site for your model.
Before you store it
Both Midea and Whynter say to drain the unit fully before storage. Midea also says to dry it and cover it, since dust and moisture left inside can lead to mold.
Size your own room with the SACC calculator, or compare all seven picks on the roundup page.