How Often Should Dehumidifiers Run in Crawl Space?

One of the places that require you to install a dehumidifier is your crawl space and basement. These two areas get dumpy relatively often. It’d be best to install the unit to address the dampness before creating a water damage menace. And even though installing it will serve its purpose, it might not be as effective as it should be if you don’t run it enough. So, how often should dehumidifiers run in crawl space?

The rule of thumb is, as often as you can. Typically, Crawl space and basement dehumidification require the humidifier to run for at least 12 hours a day. However, how often you can run the unit is affected by a few metrics:

  • Its first run
  • Humidity level
  • Extraction capacity, and
  • Rh factor

If you have or planning to get a crawl space dehumidifier, it’d be best to understand how often you need to run to maximize its effectiveness.

How Often Should You Run A Dehumidifier in Your Crawl Space?

Crawl space dehumidifiers are excellent units that help us control the amount of humidity in the crawl space.

It helps reduce the risk of water damage caused by the excess moisture in the air. It does also help make the room inhospitable to mold, dust mites, and other allergens.

However, it’d be best to determine how often you need to run your unit to ensure it’s able to optimize the dehumidification.

Typically, a crawl space will take around 12 hours to start operating and reach the proper humidity levels if the room isn’t dumpy.

But that could change if your crawl space is too dumpy – when the humidity levels in the air are too high. Some dehumidifiers can handle the workload within a day, and others might take quite some time.

The humidity levels can be determined using a hygrometer, an inexpensive device you can even get at a local hardware store. Typically, the ideal home humidity level, including crawl spaces, is between 30% and 60%.

Deciding on how often you need to run the unit in the crawl space will require you to understand some metrics like its first run, the room’s humidity levels, the unit’s extraction rate, and capacity, not forgetting the RH factor.

First Run

When you unpack and run the dehumidifier for the first time, the crawl space air is likely to be dumpy, which might be why you bought the unit.

If that is the case, it’d be best to set your crawl space dehumidifier to the highest setting and run it till the room humidity reaches the desired level.

How long the dehumidifier takes will depend on the humidity level and the unit’s efficiency.

Assuming you bought the right size dehumidifier and the crawl space has no significant damp sources, most models can remove the moisture to safe levels in few days. It might be longer, especially if there are wetness sources nearby.

And since the humidity might be high during the first run, the dehumidifier water collection tank might fill up relatively quickly.

And with modern models coming with automatic shutoff when the tanks fill up to avoid flooding the space, it’d be best to empty it regularly.

You could also use the continuous drainage hose if your unit has it to avoid emptying it manually. But remember, you’re working from the crawl space; you might not avoid draining the water.

Humidity level

Another factor that will affect how often you run your crawl space dehumidifier is the humidity levels in the room.

Obviously, the damper the area, the more often you will run the unit to maintain the ideal humidity level.

Also, try to check how long it takes for the humidity to rise to dangerous levels after dehumidification. The faster it takes, the more often you will need to run the dehumidifier.

Extraction Rate

The best practice of keeping crawl space humidity at the ideal level is to run the dehumidifier as often as possible. However, that will be affected by the unit’s extraction rate, which is challenging to determine.

An average crawl space dehumidifier, when operating correctly, should extract around 50 to 55% of the relative humidity.

Assuming you could run your dehumidifier safely in your crawl space for around 12 hours in a day, the time is enough to humid air in the room through the unit at least once.

That’s why the least time to run a dehumidifier is between 10-12 hours a day. But, of course, the more, the better.

Pints per Day

The maximum dehumidifier capacity will also affect how often you need to run it in the crawl space. The capacities tend to range from 25 pints, 50 pints, and 75 pints or between 6-20 liters per day, depending on the unit’s collection tank size. You could also get a dehumidifier with a 25-liter tank.

If your unit’s extraction rate is high and the water capacity tank is small, your tank emptying frequency will be pretty frequent.

And as I mentioned before, modern dehumidifiers come with an auto-shutoff feature that shuts off the unit once the tank fills with water to prevent flooding.

Even though most dehumidifiers never remove water that fills their tank in a day, it could be an issue if your crawl space is dumpy.

Some crawl space dehumidifiers, such as AlorAir Basement-Crawl Space dehumidifiers, have an enormous capacity that allows them to collect over 100 pints of water. For such a model, you need to time your unit to run at least 12 hours a day.

RH factor

The healthy relative humidity (RH) in a space, room, or building should be between 40% and 50%. If your crawl space’s humidity is above these, there is a risk of water damage, and mold might start to grow when it reaches 65%.

It’d be best to ensure the RH stays in the recommended range. If you run the dehumidifier until the crawl space’s RH reaches the ideal level, you will have to run it often to maintain it.

As I mentioned before, when you run your crawl space dehumidifier for the first time, it’s crucial to run it continuously to make sure the RH fall under 55% or until the water tank fills first.

Once the RH is under 55%, you can run the dehumidifier only for 12 hours per day. If the RH rises again, run the unit continuously until it drops.

If you’re using a crawl space dehumidifier with a built-in hydrostat, it should be able to go into sleep mode when the ideal RH levels are reached.

When Should You Turn Off Your Dehumidifier in Crawl Space?

Dehumidifiers are built to run continuously unless auto-shut when the water collection tanks fill up. You don’t have to worry.

However, unless you’re filthy reach, you will still have to pay your electric bills at the end month, and running a dehumidifier continuously could sky-rocket them. Timing is always the key here.

If it’s your first time dehumidifying the crawl space, it’d be best to run the dehumidifier flat out for a week to a month, depending on how dumpy the area is to give it time to dry the air in the crawl space and items in the room.

Additionally, the weather in your area will affect how long you run your dehumidifier. If it’s always raining, your crawl space will continue to get dumpy. Running the unit non-stop is the only option for you.

Install a hygrometer for your crawl space to alert you when the humidity levels are too high or when the ideal levels are reached during dehumidification.

Can You Leave Dehumidifier Running in Crawl Space While On Vacation?

Dehumidifiers are built to run continuously, but some do turn off automatically when the water collection trays or tanks in them fill up. The feature is there to prevent flooding and prevent the damages to the dehumidifier.

So, if you run your crawl space dehumidifier continuously, you will need to empty its water tank/tray frequently.

When going for a vacation, you can take advantage of the continuous water drain on the dehumidifier if it has one. You can connect it to a pipe and drain it directly to a drainage bucket.

Related Questions

When is the Best Time to Run a Dehumidifier in Crawl Space?

The best time is when the room feels humid, typically during the summer months, when the indoor air moisture becomes dumpy. You should also run it right away if you notice:

  • Musty odors
  • Sticky or stuffy surfaces
  • Mold or mildew growth
  • Wood rotting or warping
  • Watermarks on the crawl walls or ceilings

Keep Your Crawl Space’s Humidity Levels Ideal by Running Dehumidifier as Often as Possible

The best way to keep your crawl space’s RH levels between 40%-50%, the recommended levels, you might want to ensure you run the dehumidifier as often as possible. When running it for the first time, make sure you run it continuously as the room might be pretty dumpy, especially if you have never dehumidified it before. After this, you can run it at least 12 hours a day to help it maintain the humid level.

About the author

Sharif Hasan

I am Sharif a data-driven marketer by profession and run The Spruce Air. I am very interested in keeping good-quality air inside of my home. Besides, I love to share my air-related knowledge through my website.

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