Dehumidifiers 101: Complete Guide

If you’ve ever considered buying a dehumidifier, you may wonder if it’s worth the trouble.
 
We’re so glad you found this page because you’re about to discover what they are, how they work, what you need to consider before buying and much more. 

Just looking for something specific? Feel free to use our table of contents to get you to the right information at the click of a button. 

Read Before Buying a Dehumidifier

If you are convinced you need a dehumidifier but don’t know where to start, you’re in the right place. There are a few things to consider when looking for a unit to fit your needs.

What Size of Dehumidifier Do I Need?

Dehumidifier sizes are measured in pints rather than actual size of the unit. Common sizes are 30, 50, and 70 pints, although you can find units as low as 10-pints or as high as 100.

30-Pint

This 30-pint size is best for areas with moderate dampness of 50-60% and a square footage of 300-500 square ft. Most bedrooms, bathrooms, and other small spaces fit into this category.

50-Pint

A 50-pint is best for wet spaces where you often see damp patches on floors and walls with a humidity level of 60-80% and a square footage of 500-1200 sq ft. This includes many basements, crawl spaces, living rooms, and even a full level of a smaller home.

70-Pint

One of the larger options, a 70-pint is best for very wet spaces, including those with flooding or water damage. It can handle humidity levels of 90-100% in spaces over 1,000 square feet.

If your space is over 2,500 sq ft, you will either need multiple units or a whole house unit you can attach to your air conditioner for sufficient dehumidification.

It is vital to choose a size that fits your space. Choosing a too-small unit risks overworking the unit and it wearing out much quicker, as well as never quite hitting your desired humidity level.

How to Choose a Dehumidifier

Now that you have a good understanding of how to size a dehumidifier, here are some other considerations:

Measure the Space

This will require you to measure both length and width. Once you have these measurements, multiply them together to get total square footage

Determine Your Moisture Level

If storing sensitive equipment, documents, or tools, you may need a stronger unit than your space requires to get the humidity lower than 50%.

Size

Of course, size is the final consideration in this formula. So double check the section above before deciding on a purchase.

Dehumidifier Maintenance Tips

As with any piece of equipment you own, a dehumidifier will require some regular maintenance and care to keep it operating at its optimal level.

Common Dehumidifier Issues

Here are some common problems that may come up in a dehumidifier.

Dehumidifier Freezes Up

This can occur for a bunch of reasons. First, if the ambient temperature is lower than 65 degrees, this can cause freezing. Other causes include incorrect humidity setting, issues with the fan motor, blower wheel, or decreased airflow. Each of these should be checked to determine the problem.

Not Collecting Water

If the tank seems empty all of the time, you should start by checking and changing the filters. Poor airflow is often the issue here and can result from a broken fan motor. Another thing to check is that the coils are not frozen. If none of these seem to be the issue, you’ll likely need to call a professional.

Not Reaching Desired Humidity Levels

First off, check the size of your unit to be sure it is sufficient for your space. This is a common error and will cause the unit to underperform. Secondly, check the humidistat, if included, to be sure it is set at the proper level. Lastly, check the coils for frost and be sure there is the proper amount of refrigerant.

Dehumidifier Troubleshooting

Any time you have an issue with your dehumidifier, it can be frustrating. Whether your unit is leaking, frozen, not blowing air, or not collecting water, here are some simple steps to follow:

• Unplug the unit and allow to cool
• Evaluate the ambient temperature- is it too cold?
• If the temperature is under 65 degrees F, check for frozen coils
• Inspect the filter for damage and clogs
• Clean the unit to remove dust, sediment, and put in a new filter
• Check humidistat settings
• Listen for clicking. If the unit clicks when turned on but doesn’t operate, this indicates that the                        compressor has gone bad
• Check the fan motor to be sure it is operating, oil if necessary
• Locate the capacitor inside the compressor and test with a multimeter- replace if necessary
• Check refrigerant levels and call a professional for a recharge if levels are low
• If you are a handyman with electrical skills, you can also check the overload device for a short circuit
  
  If none of these tips help get your dehumidifier up and running, your best bet is to call a repairman. This can be costly, but depending on the type of unit, can be more cost-efficient than buying a new one.

How to Install a Dehumidifier

Installing a portable dehumidifier is a simple task. If you are installing a whole-house unit, the task will be more difficult and generally requires a professional.

Install a Portable Dehumidifier

Here are the steps to installing a portable dehumidifier:

1. Decide on the best placement- the unit needs plenty of space around it to circulate air and should be located in the area you need the humidity reduced most
    
2. Run the hose if self-draining. The hose will need to be placed near a drain or sink. If no pump is being used, the hose needs to be lower than the unit so gravity can draw the water down. If a pump is used, this consideration is unnecessary
    
3. Plug the dehumidifier in and turn it on
   
   
4. Choose your dehumidifier’s settings. Most units will allow you to set a specified humidity level. Some humidity is beneficial so 30-50% humidity is the recommended range
   
   
5. Once the dehumidifier is running, check back often to ensure moisture is being removed and the tank is not full

Install a Whole House Dehumidifier

1. First, decide where your dehumidifier will be mounted. This is often in an attic or near the current HVAC unit
   
   
2. Attach appropriate ducting to both the AC and dehumidifier. Be sure to do this based on the flow of air
    
3. The supply duct should be located in a humid area of the house
   
   
4. Run or attach into an existing condensate line to drain water
   
   
5. Install the filter
   
   
6. Add a humidistat- this should be located near the thermostat
   
   
7. Plug dehumidifier in
   
   
8. Choose the desired humidity level and turn the unit on

Listed above are basic steps for a whole house dehumidifier installation. Please refer to the user manual for the complete steps specific to your unit. For some visual details, check out the video below.

How to Clean a Dehumidifier 

Cleaning a portable dehumidifier isn’t a difficult task. It only requires a few cleaning items and a bit of time. Anyone can do it.

Cleaning a Portable Dehumidifier

• Make sure your unit is unplugged for safety
  
  
• Wipe down the outside of the dehumidifier with a damp cloth- avoid getting electrical control panels wet. If they need to be cleaned, use a dry cloth
  
  
• Remove the reservoir/bucket and wash with dish soap and water
  
  
• Fill reservoir/bucket with ½ vinegar and ½ water and allow to soak while you complete the rest the task
  
  
• Clean/change air filters- this depends on the filters your unit uses. Some of these can be rinsed and others are disposable and should be replaced with a new filter
  
  
• Clean the bucket filter- this tiny device captures impurities from the air and traps them. This should be emptied and rinsed according to your dehumidifier’s user manual
  
  
• Wipe down coils
  
  
• Rinse reservoir/bucket well
  
  
• Reassemble all parts and plug in the unit.

How Often Should I Clean a Dehumidifier?

Portable dehumidifiers should have a basic cleaning as often as once per week. This involves emptying the tank, checking and washing the filter, and wiping down the unit. Performing a regular cleaning will prevent mold build-up and allow your unit to function optimally and last as long as possible.
 
The full cleaning listed above should be done once per month, or when the unit has been unused for an extended period of time.

When is it Time to Replace My Dehumidifier?

Dehumidifiers typically last 3-5 years, although some last much longer. However, there are some other indications that a dehumidifier need to be replaced include:

• It switches on and off regularly (called short cycling)
• Not reaching the target humidity level- this either means your unit is not performing properly or is the wrong size
• You smell mold every time it runs- this could mean mold is growing inside where it can’t be reached'
• Not collecting water even after cleaning and maintenance
• Unit is hot to the touch most of the time- while it may get warm when in operation, if it is hotter than normal, it may indicate an issue
  
  If your dehumidifier isn’t performing, a recharge is an option to consider as well. Refrigerants are required to cool the air to extract moisture, and if the level is low, it may need to recharge your dehumidifier. However, this is usually something that needs to be done by a professional.