What Size Dehumidifier Do I Need? A Guide to Choosing the Right Model

If your home smells musty or damp, chances are you need a dehumidifier. We'll help you choose the right size for your room.

Water condensation is a sign of high humidity levels—a problem that can occur year-round. High humidity can also cause health complications, especially for people who suffer from chronic respiratory diseases. And mold can further aggravate the situation.

You might expect humidity in certain seasons and regions, but even during winter condensation on the inner surface of windows makes it easy for mold and mildew to grow. Unless exterior walls are properly sealed, condensation can rot the structure and moisture can ruin insulation. Cracked exterior paint and peeling or blistering siding are signs of a problem.

Kyle Shirley of Denver-based roofing company Sol Vista Roofing adds that "if a roof leak caused water damage to the interior of your home, it's important to get the moisture cleared as quickly as possible. Interior moisture that festers can cause mold, mildew, and wood rot and lead to more extensive (and expensive) home repairs."

person turning on dehumidifier
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Kitchen and bathroom exhaust fans, as well as air conditioning, can help reduce humidity. But if you don't have these or the weather is too cold to turn on the AC, a dehumidifier is the best option.

Dehumidifiers are designed to extract excess moisture from indoor air, making interior spaces comfortable and healthy for occupants. Dehumidifiers differ in design, shape, size, and functionality. Here's what you need to consider to find the right dehumidifier for your home.

How to Choose a Dehumidifier

1. Define Your 'Why'

First, define why you need a dehumidifier. Do you need one for the whole house or a portable unit for specific rooms? Do you need to dry out water accumulating in a wall or roof, or do you simply want to improve the air quality in the room? This will help narrow down the choices to the device that is the most efficient to meet your needs.

2. Types of Dehumidifiers

There are many types of dehumidifiers, but these are the common terms to search for:

Thermo-electric (or Peltier) models use electricity to create temperature changes within the systems' modules.

Refrigerant models are good all year-long and they function like an air conditioning unit.

Desiccant models can extract a lot of water. They are best for industrial spaces or major floods and leaks.

3. What Dehumidifier Size to Get

If humidity is a problem throughout your entire home, look for a whole-house dehumidifier, which has the capacity to extract moisture from 2,500–4,000-square-foot spaces.

Most people opt for a portable unit that can treat trouble spots during certain times of the year. The capacity of the device you need will depend on the space available to place it and the amount of moisture you need to extract from the room. You'll need to measure the square footage of the room you want to dehumidify and have a rough idea of the moisture levels.

You can check moisture levels using a humidity meter, typically found in a home inspector's kit. Or you can just eyeball it. Can you see water spots on the walls or ceilings? Is the room damp or wet? Is there any visible or standing water? If you answered yes to any of these questions, then you need to remedy the source—stop any leaks, seal any pipes, or clean any drains and gutters—before buying a dehumidifier sized to do the trick.

If your roof is leaking, Shirley says that the priority is to fix the leak first then get a dehumidifier. "If you have a large wet area that is saturated with rainwater, aim to get a dehumidifier rated to remove 40 or more pints per day of water. For leaks that resulted in little more than some interior dampness, you can likely get by with a unit that is rated to remove 30 pints per day or less," he suggests.

A dehumidifier's drying capacity depends on the amount of water it can remove from the air in 24 hours. A higher capacity will create maximum efficiency, but it can be loud and uses more electricity.

Dehumidifier capacity is measured in pints of water that can be removed in a day. Since moisture levels vary by space, it is best to consider a range. A 34–40-pint capacity dehumidifier can cover a 500-1,500 sq. ft. room, while a 40–60-pint capacity dehumidifier can cover a 1,000–2,500 sq. ft. room. A large 60+ pint capacity is used to tackle 2,500 square feet and up. But if you want to dehumidify an entire house, consider a non-portable device that is well placed.

4. Humidity Control

Dehumidifiers with automated controls for monitoring and setting humidity levels are always a good choice. The ideal humidity level should be between 40–50% in the summer and 30–50% in winter. A dehumidifier with a built-in hygrometer can measure humidity levels and display them. If it has an adjustable humidistat, you can dial in the desired humidity level that the machine will automatically maintain.

5. Dehumidifier Tank Capacity

Your dehumidifiers' tank capacity will determine the number of times you need to empty its tank. A dehumidifier with a larger water capacity is ideal for lots of moisture, but it is likely to cost more than smaller tanks.

Also, consider getting a dehumidifier with continuous drainage. Changing the water tank every day can become tiresome. Many portable dehumidifiers have a hose that you can place near a drain to allow the dehumidifier to self-drain. Some types of dehumidifiers use evaporation technology that uses an energy-efficient heat pump rather than a drain.

6. Operational Factors

Other factors to consider when choosing a dehumidifier are the noise level and energy consumption. If you plan to run the dehumidifier all night long, you'll want it to be quiet. Consider one with a low noise level under 45 decibels.

Check the manufacturer's label for energy efficiency or multi-use. If you choose a device with a laundry mode feature, you can dry clothes indoors. You'll definitely see your energy bill rise, but the cost depends on the number of hours per day you'll need it to work.

7. Ease of Use

Some features make portable dehumidifiers easier to use:

Auto shut-off saves energy. When the desired humidity level is reached or when the tank is full, the machine shuts itself off.

Smart features like an adjustable humidistat, built-in hygrometer, full-tank indicator, and Alexa or app support can help the whole family use the dehumidifier.

Portability is a vital feature if you intend to use the unit in multiple rooms. Ensure it is lightweight and comes with wheels.

Easy cleaning and maintenance are major factors. Make sure the dehumidifier you choose is easy to assemble and disassemble.

Filters can help clear large particles, germs, and dust to give you better-quality air. If your home always feels musty or gets dusty, consider getting a dehumidifier with a filter option so that you don't have to buy another device.

Warranties might be the last thing on your mind, but any time there's water near an electrical device you'll want assurances of repair or replacement within a reasonable timeframe.

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