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Whole House Dehumidifiers: Why You Need One & How to Choose the Right Size

installed dehumidifier

Originally posted 3/5/20, updated 12/14/22

If you’ve ever been in the Midwest just before a thunderstorm, you know how intense humidity can be.  The air is a damp sweaty cloth wrapped around you like a boa constrictor. It weighs you down and slowly compresses you, until you feel both smothered and drowned at the same time. It’s hard to breathe, you’re sweaty and uncomfortable, and every moment spent in this haze lasts three times as long as it should.

This is NOT a feeling you want in your house.  We all know how critical good sleep is for our overall health, and all the studies agree: the best sleep conditions are between 60° and 70° Fahrenheit with 50% humidity.  The best way to achieve these conditions is a fully operational HVAC unit and a dehumidifier.

Since opening our doors in 1996, Acculevel has installed water drainage into thousands of homes, and many of these have included whole-house dehumidifiers.  A dehumidifier is an important component in waterproofing your basement or crawl space, and they are an absolute necessity for encapsulation


How Does a Dehumidifier Work?

Dehumidifiers reduce humidity by pulling moisture from the air.  The air is filtered and cooled, and this process converts the humidity into condensation.  As the condensation accumulates, it’s stored in a tank that must be emptied, or drained through a water line that connects to your sump pump.

You may be tempted to use your HVAC system to do the work of a dehumidifier.  Some HVAC systems even offer these as add-on options.  But we don’t recommend this as a practical solution.  Your HVAC unit’s primary function is not to remove humidity; using it to do so is going to cause it to work harder (and differently) than it was intended to do. It’s far less expensive to buy a dehumidifier than it is to repair or replace an HVAC that gets overworked and fails.


4 Reasons You Need a Dehumidifier For Your Home

You should install a dehumidifier in your home for three major reasons: it improves your health, enhances your environment, and saves you money.     

  1. Clean air that is free of allergens and mold is easier to breathe, especially if you have allergies or asthma. High humidity helps ‘feed’ mold spores, and contributes to musty stale odors.  Breathing in mold spores is not good for anyone; even healthy people can be adversely affected.   By taking excess moisture out of the air, the dehumidifier makes your air cleaner and safer.
  2. Excess moisture isn’t good for your environment, either.  It degrades your home’s stability, because dampness will rot the wooden structure.  Moisture and humidity are often the cause of sagging floors, which can be expensive to repair.  We all know that dampness is a Very Bad Thing when mixed with electronics- but it’s not good for your furniture or textiles, either.  In fact, unless you’re a fish, a drier environment is better. 
  3. If you have a dehumidifier removing excess humidity, your house will feel cooler in the summer.  This can allow you to set the thermostat a few degrees higher.  Drier air is easier for your HVAC unit to process.  And if it doesn’t have to run as often, your energy costs will decrease also.
  4. A recent study demonstrates dehumidifiers are efficient at removing viruses from the air.  If you look at the table below, you’ll see that there’s a clear mark at the 50% humidity level.  This reduces or eliminates bacteria, viruses, fungi, mites, allergens, and reduces your chances of a respiratory infection.

Chart for humidity levelsInformation taken from a study performed by ASHRAE (the American Society of Heating, Refrigerating and Air-Conditioning Engineers.)


Whole Home Vs. Portable Dehumidifier  

The benefits of a dehumidifier for your home make sense. But what are the other options for your home? Can you choose a room-size, or portable, dehumidifier?  Yes, you can. But there are 3 major drawbacks.

  1. It will be less efficient.  Your house is not vacuum-sealed between rooms or floors.  If a machine is pulling humidity from your basement, it’s not going to get rid of the humidity on the first floor.  And that humidity will spread, funneling moisture downstairs in an endless flow. This endless supply means the dehumidifier will never shut off, which leads us to the next item on our list….
  2. It won’t last as long.  If you are trying to remove humidity from a house at the height of summer, and you’re only using a portable unit, it’s going to run all the time.  This isn’t good for any motor, no matter how well built it may be.
  3. A dehumidifier running constantly costs a significant amount of energy- and not just electricity.  Portable units have to be emptied, and that means you have to remember to check it, haul the water to a bathroom or kitchen to dump it, then put the tank back. 

The biggest benefit to a portable dehumidifier is that it costs less than a house-sized unit.  Everyone has a budget, and we recognize that a higher initial cost can be unpleasant. We recommend that you consider this an investment that protects your entire home and its furnishings.  

It will ultimately pay for itself in reduced energy costs and improved quality of living. Here at Acculevel, we install dehumidifiers with a capacity of 95 pints (45 liters) for $2175-$2650 (cost includes installation).  This model comes with a 5 year warranty, is made in America, and has an average life span of about 15 years.   

This picture was taken by an Acculevel crew member after installation.
installed dehumidifier
This shows a fully encapsulated crawl space with a dehumidifier.  The drainage line connects directly to the sump pump system, so there is no tank to empty.

What Size Dehumidifier Do I Need?

Dehumidifiers are sold by capacity.  The capacity refers to the amount of moisture that the model can remove in a single day.  You need to know two things to calculate the necessary capacity: condition and square footage.  

The condition may also be referred to as moisture level or dampness level, depending on which manufacturer’s chart you’re reading.  Condition can be somewhat subjective, especially if your home has a crawl space and you aren’t able to observe the surfaces in it. If you would like specific data, you can purchase a hygrometer at your local hardware store and get a precise reading.  

FYI: The ideal RHL (relative humidity level) is between 30%-50%.

Your home’s square footage is probably common knowledge to you.  If you don’t remember it and don’t want to run the numbers, square footage should be clearly indicated in your home’s realty paperwork.  However, if you have a crawl space, you will probably need to calculate and add that area’s footage; most listings and inspection reports don’t include crawl spaces in a home’s square footage because it’s not ‘living’ space.

For our example, we’ll use a 2500 square foot home:

ConditionTypical SymptomsCapacity
Slightly Damp 50%-60%During humid weather, the air feels clammy and has musty odors 26 pints (12 liters)
Damp 60%-70%Always feels clammy, with odors and some moist patches in the basement/crawl space32 pints (15 liters)
Very Damp 70%-80%Moisture is collecting or beading on surfaces in basement/crawl space38 pints (18 liters)
Wet 80%-100%Standing water in basement/crawl space*44 pints (21 liters)


Our Recommendations

We suggest that you buy a model a level above what you need.  This way your unit won’t have to operate at maximum speed to maintain a good RHL.  This is good for you and the dehumidifier because: 

  • You’ll save money, because this will take less energy.  
  • A machine running at a lower setting is quieter, giving you a more harmonious space. 
  • It will also reduce the wear and tear on the machine, allowing it to last longer.

We also urge you to have your foundation evaluated, if you have a wet basement or crawl space. This level of humidity is not healthy for you or your home.  We have a guide to basement waterproofing here, or this blog that explains how a wet crawl space can damage your home

How Do I Move Forward?

If you are interested in waterproofing, having a dehumidifier installed in your home, or other foundation repairs:  locate an experienced local foundation company, and make an appointment. Before you sign a contract for any service, you should always verify the company is reputable, insured, and accredited by the Better Business Bureau.  

If you live in Indiana or the surrounding states, contact Acculevel.  Established in 1996, we specialize in waterproofing and foundation repairs.




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