How Often and How Do You Empty a Portable AC?

Portable air conditioners are inexpensive, easy to install and very convenient if you have a small house or if you only need to cool a certain room in the house. One of their disadvantages however is that you need to manually empty the drain tank/bucket.

Some portable air conditioners models allow you to connect a drain hose and automatically drain the condensate to the outside or to a house drain but most don’t or are messy.

portable air conditioner

So, how often do you need to empty a portable air conditioner? Or rather after how long should you empty a portable air conditioner?

Usually, portable air conditioners need to be emptied after 8 hours. However, some units can be used for up to a month without the need to empty them especially in dry areas. The frequency of emptying portable air conditioners depends on the humidity levels, usage and settings.

As a rule of thumb, you should make a habit to empty your portable air conditioner at least once per day. However, if you live in a really dry place (low humidity area) and the unit hardly has any water at the end of the day, you can schedule to empty it weekly.

In some cases, you will notice that your portable air conditioner is filling water quickly than usual. Unless you live in a very humid location, that is usually a sign that the unit is not working as it should.

Not all portable air conditioners need to be drained. Self-evaporating portable air conditioners heat up the condensate and exhaust the water vapor together with the hot air to the outside using the unit’s exhaust hose.

Although the primary function of air conditioners is cooling the indoor air, they also help to reduce the relative humidity in the house. As the air is being cooled by the cooling coils, the moisture in the air condenses and drips off inside the condensate tank.

Central, mini-split and window conditioners have a way to automatically drain the condensate from drain pan but portable AC almost always need to be manually emptied. Self-evaporating units however use the heat removed from the air to evaporate and remove the moisture through the exhaust hose.

Failure to empty the portable air conditioner when its condensate drain tank is full will cause it to turn off. That is a fail-safe method used to prevent the tank from overflowing with water which could damage the house.

Factors Determining How Often to Empty a Portable Air Conditioner

It is frustrating when you are looking for a simple answer to a question only to be slapped with “it depends”. This is one of those times.

To be honest, there is no a simple answer on how often to empty a portable AC unit. It will depend on the following factors:

  • Relative humidity
  • Settings
  • Usage
  • Unit model/brand

The status of the portable AC unit also determines how much water it produces and hence how often you need to empty it. Poorly maintained AC units will fill up with water quickly thereby needing to be emptied frequently.

1. Relative Humidity

condensation on window

Relative humidity is basically the amount of water vapor in the air, expressed as a percentage of the total amount of water that the air can hold at that temperature. “At that temperature” is bolded because temperature directly affects the relative humidity.

During summer when temperatures are high, relative humidity is high but when temperatures fall in winter the relative humidity levels also fall. However, there is more to relative humidity than just temperature.

Location also plays a big role in determining the relative humidity. Coastal areas have high humidity than areas farther away from water bodies. That is the reason why humidity in Florida is higher than that of Arizona, despite Arizona being quite hot in the summer.

As I mentioned, air conditioners dehumidify the house apart from just cooling the air. If there is a portable air conditioner in Florida where average humidity is 74.5% and another similar unit in Arizona where average humidity is 38.5%, you can expect the unit in Florida to be emptied way more frequently than the one in Arizona.

The air in Florida is concentrated with water vapor while the air in Arizona is hot but dry. As a result, there is a lot of condensation on the Florida’s unit coil while there is almost none in the Arizona unit.

2. Settings

How low or high have you set your portable air conditioner temperature? If you have set it too low, perhaps in a bid to cool a bigger room, it means that the indoor air is being cooled to colder degree which also means that more condensation is taking place and more water is being formed.

Therefore portable AC with low temperature settings will produce more condensate and will need to be drained more frequently than units set at normal settings.

3. Usage

How long do you use your portable air conditioner in a day? Does it run for only a few hours or it runs day and night?

Needless to say, the more the AC unit cycles air through the cooling coils the more water it produces. As long as the indoor air is humid condensation will keep taking place.

Portable air conditioners that run for long hours will need to be emptied more frequently than those which only run for a few hours in a day.

4. Unit Model/Brand

All portable air conditioners are not made equal. Some are bigger than other (with big condensate tanks) and some are more modern and efficient than others.

To start with, if you have a small portable AC unit, it means it also has a small condensate drain tank which will fill up quicker than another bigger unit used to cool a room of a similar size.

As I mentioned, some units will use the condensate to cool the evaporator coil hence turn it from liquid to gas and is afterwards exhausted out. Such units will not need regular emptying.

Also, if you have a single-hose portable AC unit, it is normal for such units to create negative air pressure inside the room, forcing humid air from outside the room to be sucked in. If the air being sucked in is quite humid (like from the bathroom, kitchen or basement), the tank will fill up quickly necessitating to be emptied.

On the other hand, dual-hose portable AC are properly vented and may take longer to fill up the condensate drain tank.

What Happens if You Don’t Empty Your Portable Air Conditioner?

One of the first thing that will happen if you don’t empty your portable air conditioner is that it will automatically turn off. The AC condensate drain tank has a float switch which if water level exceeds the set level level it cuts off power to the unit forcing it to turn off

When the unit is off, not only will it fail to cool your indoor air but it will also stop producing more water. If air cannot cycle through the evaporator/cooling coil, condensation cannot occur. This systems prevents the unit from overflowing and flooding your house.

If somehow the system does not work, the tank will fill with water and overflow. That can really damage your house especially if you have a wooden floor.

Leaving the condensate drain tank with water also creates a humid environment for mold to grow. Within no time, there will be a musty smell coming from your air conditioner.

How to Drain a Portable AC with Hose

If you are tired of manually draining your portable AC, there is an easy method you can use to drain it automatically.

  • Check the size and type of drain port at the rear end of your unit.
  • Purchase a drain hose and a connector elbow fitting to match your unit.
  • Turn off the unit and drain out the water in the tank.
  • disconnect exhaust hose.
  • Connect the elbow fitting to the drain port and then the drain hose to the fitting.
  • Direct the other end of the hose to a floor drain, outside or to a sink drain.
  • connect exhaust hose back.
  • Turn on the unit and check if it will drain properly.

To allow your unit to drain efficiently with the help of gravity, you can place it in an elevated position like on top of a stool.

Why Your Portable AC Fills with Water Quickly

The main reason why portable ACs fill with water quickly is high humidity. If the relative humidity in your area is high, the unit is not faulty and is just doing its job.

Dirty air filter or evaporator coil could also be the reason. They restrict the flow of air to the unit forcing more condensation to take place and/or the evaporator coil to freeze. Eventually when the ice starts to melt, the unit fills with water quickly.

A new unit or one which is being turned on the first time in the season could also make water fill the condensate tank quicker than is the norm. Since there will be lots of moisture trapped in the house (in carpets, rugs, furniture etc.) the first few days the unit will be pulling out that moisture causing the tank to fill up quickly.

Humid air coming from the outside can also make the tank fill up quickly. That is especially if you have opened windows, crawlspace with no vapor barriers, unfinished basement or open crawlspace vents.

Other reasons are:

  • Faulty condensate pump
  • Clogged drain holes
  • Bad fan blower
  • Clogged condensate drain line

For more information on this subject, check out this post. And basically that is all on the frequency of emptying portable air conditioners and the related queries.