How Often Do You Need to Drain a Portable Air Conditioner?

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Portable air conditioners need regular maintenance to function properly. Among them, draining the condensate tank is an important task to keep your portable AC running.

The frequency that you drain your portable air conditioner depends on the conditions of the air inside your home.

In this article, I’ll discuss how often you need to drain your portable air conditioner. We’ll also take a look at what happens if you don’t drain your portable air conditioner.

How often should you drain your portable AC?

Depending on the humidity in your space, you will need to drain your portable air conditioner as often as every 8 hours. However, you usually won’t need to drain your portable air conditioner this often.

If you live in a dry area, then you will rarely need to drain your portable air conditioner. This is because the water that fills your portable air conditioner is extracted from the cooling of warm humid air. If the air in your space is dry, then the air conditioner won’t pull any moisture out of the air.

Most modern portable air conditioners are able to completely remove moisture from your home using the exhaust vent. To do this, the air conditioner sprays water from its condensate tank onto the condenser coil. As the condensate comes into contact with the hot condenser coil, it evaporates. The vapor is then blown out of your house through the exhaust hose.

Most times, this method is able to get rid of the water from your portable air conditioner’s condensate tank. However, if the humidity in your home is excessively high, your portable AC won’t be able to evaporate all the water. Only in humid climates will your portable air conditioner’s tank need to be emptied regularly.

Even if you live in a dry area, you need to make it a habit to check your portable AC’s tank at least once a month. It will give you a chance to inspect your portable air conditioner’s tank for any signs of mold.

How often to drain portable AC infographic

What happens if you don’t drain your portable air conditioner

If you don’t drain your portable air conditioner, a few things can happen:

  • The portable air conditioner will shut off and not turn back on. This is the most common outcome. Most portable air conditioners have a built-in float switch. The purpose of the float switch is to turn off the air conditioner if its condensate tank fills up with water. When an air conditioner has a full tank, then it is usually accompanied by an alarm that will alert you of its status. That way, you’ll know it’s time to drain the tank.

  • The condensate tank will overflow. If your portable air conditioner’s float switch is not working, then you run the risk of water overflow. This is not a huge problem in and of itself, except that it can cause water damage to your home.
  • Mold will grow in your portable air conditioner. Most people don’t consider that mold can grow in their AC. Mold growth happens especially in portable air conditioners that are not emptied. If water is left inside your portable AC’s tank, it creates a moist environment that is perfect for a mold colony to grow in.
portable ac dirty drain pan

Why your portable air conditioner is producing so much water

A portable air conditioner that produces a lot of water is nothing to be worried about. Well, most of the time anyway.

Air conditioners produce water as they cool your home’s warm air. As your home’s air is cooled, water precipitates out of the air and is collected in a tank in the AC.

In fact, this method of removing water from the air is how dehumidification works.

If your portable air conditioner is producing more water than it usually does, it is because your room’s air is more humid than usual.

This can be due to internal or external factors:

  • Internal: Activities such as cooking and using the shower will generate humidity. If you have a lot of guests over, then the humidity can increase from all the people breathing inside your home. 
  • External: Humidity can come from outside your home as well. If the weather outside is warm and humid, then your air conditioner will produce water as it cools and dehumidifies the warm moist air.

The production of water is a good sign that your air conditioner is functioning correctly. But if it is producing more water than usual, that can be a sign that there is a source of humidity that is infiltrating your home’s air.

In this case, you’ll need to find the source of humidity and remove it. One source of excess humidity is the infiltration of outside air into your home. Gaps around windows and doors can let warm moist air from the outside into your home.

Be sure that you seal all the gaps in your home to not allow outside air and humidity to get inside.

How long can you run a portable air conditioner continuously?

The short answer is that you can run your portable air conditioner continuously without much issue. As long as you clean the air filters and empty the condensate tank, you can pretty much run your air conditioner all season long.

But that doesn’t mean that you should just leave your AC on all the time. Like most mechanical equipment, it is a good idea to give your portable AC periodic breaks. Turning off your portable air conditioner gives it a chance to cool down and stop wear on its parts.

Regardless if you turn your AC off, it should turn itself off periodically after it cools a room. A sufficiently sized air conditioner will run in 10-20 minute intervals as it cools your room down to the temperature setpoint.

If your portable air conditioner runs constantly, then it may be undersized for the room. There may also be extra sources of heat or moisture that need to be isolated from the room. In both cases, a larger portable air conditioner will cool your room quicker and more efficiently.

Continuous drain setup for portable air conditioner

If you want your portable air conditioner to continuously run, then you’ll need to set up a drain hose.

The drain hose empties water from the condensate tank automatically. One side of the drain hose attaches to the condensate tank and the other side goes to a drain. You can also direct the condensate hose outside to drain.

Using a drain hose will prevent your condensate tank from accumulating water. With this setup, you won’t need to worry about emptying the condensate tank.

But you’ll still want to keep an eye on your portable AC. The inside of the portable air conditioner will still be a little wet from the condensate. Remember to check for mold and clean the filters at least once a month.

Hi, my name is Trey Lewis and I’m the founder and chief editor at HVAC Training Shop. My goal for this website is to help homeowners troubleshoot and maintain their home’s HVAC systems. Whether it’s changing an air filter, troubleshooting a blower motor, or just buying a new humidifier, I want to make sure that you’re covered.

2 thoughts on “How Often Do You Need to Drain a Portable Air Conditioner?”

  1. I have a portable air condition in a small 8×12 shed we finished off for my teen to use as an apartment. So Florida is very humid, and on cool mode we have to empty the tank every couple hours. Im thinking I should drill to set up continuous drainage so we don’t have to keep draining it… any better ideas?

    • Hi Matt,

      A continuous drainage setup is your best bet if you don’t want to keep emptying the portable AC.

      Another option would be to install a window unit. In addition to not needing to drain, window units are generally more energy efficient.

      Hope this helps,


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