A dehumidifier is an air conditioning device which reduces and maintains the level of humidity in the air. This is done usually for health or thermal comfort reasons or to eliminate musty odor and to prevent the growth of mildew by extracting water from the air. It can be used for household, commercial, or industrial applications. Large dehumidifiers are used in commercial buildings such as indoor ice rinks and swimming pools, as well as manufacturing plants or storage warehouses.
If you’ve ever used the words musty, muggy, dank, fuggy, wet, mildewy, or the dreaded moist to describe the air in your home, you may get relief from a dehumidifier. High humidity can cause all kinds of problems. It can make clothing go moldy in your cupboard, it’s bad for computers (it can cause rusting or short circuits inside their cases) and optical equipment (that’s why things like cameras and binoculars are sold with water-absorbing sachets of silica gel)¡ªand it’s bad for your health too.
- 1 Health Benefits of Using a Dehumidifier
- 2 When You Might Not Need a Dehumidifier
- 3 How Dehumidifiers Work: The Core Mechanism
- 4 Comparing Dehumidifier Types
- 5 Key Features to Look for in a Dehumidifier
- 6 How to Use a Dehumidifier Effectively
- 7 Best Practices for Reducing Humidity
- 8 Best Dehumidifier Recommendations
- 9 Frequently Asked Questions (FAQs)
- 10 Additional Resources
Health Benefits of Using a Dehumidifier
A dehumidifier does have some established health benefits. If you or your family members have asthma or allergies, a dehumidifier might help relieve symptoms and make breathing easier. By reducing the humidity in your home, you can also help to reduce asthma symptoms and irritation. Dehumidifiers work best in areas where damp air collects, like basements. Signs you might want to consider buying a dehumidifier include:
- Anyone in the home has a prolonged allergy season, year after year.
- You’ve recently moved and your allergies seem to be flaring up more often or worse than they used to.
- Musty odors, clammy conditions, and condensation on the walls, windows, or ceiling.
When You Might Not Need a Dehumidifier
Dehumidifiers make the air more dry. If you live in an already dry climate (such as a desert or high-altitude area), or use gas or electricity to heat your home, a dehumidifier might not be needed. Conditions like pneumonia can actually become worse if the air is made too dry. Your skin and hair can be affected, too, if your home becomes an arid place. People with eczema (atopic dermatitis) may be especially prone to flare-ups in a dry environment. When you use a dehumidifier, you might need to be especially mindful of staying hydrated.
How Dehumidifiers Work: The Core Mechanism
A dehumidifier is a bit like a vacuum cleaner: it sucks in air from your room at one end, takes the moisture out of it, and then blows it back out into the room again. The moisture drips through into a collection tank that you have to empty, from time to time. Dehumidifiers work in one of two ways¡ªby refrigeration (cooling air to remove moisture using similar technology to a refrigerator or air conditioner) or by absorption/adsorption (where moisture is absorbed into or adsorbed onto a drying material and then removed).
Refrigerant-Based Dehumidifiers
Electric refrigeration dehumidifiers are the most common type of dehumidifiers. They work by drawing moist air over a refrigerated evaporator with a fan. The cold evaporator coil of the refrigeration device condenses the water, which is removed, and then the air is reheated by the condenser coil. The now dehumidified, re-warmed air is released into the room. This process works most effectively at higher ambient temperatures with a high dew point temperature. In cold climates, the process is less effective. Highest efficiency is reached above 20 ¡ãC (68 ¡ãF) and 45% relative humidity.
The mechanics behind a refrigerant-style dehumidifier are actually quite simple. Have you ever noticed how moisture forms on the outside of a cold glass of water on a hot day? That’s condensation, and once you know that, understanding how a dehumidifier works becomes a lot easier. Specifically, warm, moist air is drawn into the dehumidifier by a fan and then crosses over the refrigerant-cooled coils. This process causes the moisture passing through the dehumidifier to condense on the coils within the machine. As this air cools, its ability to hold and retain moisture diminishes. Once the air has more moisture than it can hold, it forms condensation.
Desiccant Dehumidifiers
Desiccant dehumidifiers (known also as absorption dehumidifiers) bond moisture with hydrophilic materials such as silica gel. Cheap domestic units contain single-use hydrophilic substance cartridges, gel, or powder. Larger commercial units regenerate the sorbent by using hot air to remove moisture and expel humid air outside the room. The most used desiccant dehumidifier is the rotary desiccant system, which works by trapping moisture using a revolving wheel when the vapor pressure on the surface is less than that of the air passing by. The desiccant wheel features two airstreams for air to pass through, each isolated by a seal. The desiccant dehumidifier pulls in humid air from the room through an intake fan, and the desiccant wheel absorbs moisture from the airstream as it travels through the machine.
Other Types of Dehumidifiers
- Thermo-electric Dehumidifiers: Operate with charged plates that convert electricity into a temperature difference that helps dehumidification. This type has low capacity and is less efficient than condenser dehumidifiers.
- Heat Pump Dehumidifiers: Use a fan, heat pump, and heat exchange coils to remove moisture from the air. Moisture condenses and collects, and dryer air circulates back into the home.
- Dehumidifying Ventilators: Use a sensor to detect moisture levels and an exhaust fan to expel air outside, often used in basements, attics, and crawl spaces.
Comparing Dehumidifier Types
| Type | Mechanism | Best Use Case | Pros | Cons |
|---|---|---|---|---|
| Refrigerant | Uses refrigerated coils to condense moisture | Warm, humid environments | Highly efficient at room temperature, widely available | Less effective in cold climates, can be noisy |
| Desiccant | Absorbs moisture with hydrophilic materials | Cooler environments, garages, workshops | Works well in low temperatures, quieter operation | Higher energy consumption, less economical |
| Thermo-electric | Uses charged plates for temperature difference | Small spaces, low humidity | Compact, low maintenance | Low capacity, less efficient |
| Heat Pump | Uses heat exchange coils to condense moisture | Residential spaces with moderate humidity | Efficient for home use, reliable | May require professional installation |
Key Features to Look for in a Dehumidifier
When it comes to selecting a dehumidifier, you need to consider the pint capacity and size of your space. Many dehumidifiers are equipped with a humidistat, which measures and can set the relative humidity (rh) in a room. A 50 percent rh is recommended for summer, while in winter, the ideal rh can be as low as 30 percent. Here are some key features to consider:
- Humidistat: Detects the moisture level in the air and powers the unit on when necessary.
- Auto-Shutoff: The dehumidifier will automatically shut off when the drainage bucket is full.
- Continuous Drainage: Some models have an option to attach a hose that can be directed to a sink, floor drain, or sump pump for drainage.
- Energy Efficiency: Choosing an ENERGY STAR certified dehumidifier can deliver savings on energy bills without sacrificing performance, features, and comfort, while protecting the environment by reducing greenhouse gas emissions.
How to Use a Dehumidifier Effectively
Placement and Setup
- Pick the right spot. Placement is key. Be sure to allow enough room for air to freely flow into and out of the dehumidifier. Most models release air through vents on the top, but a few vent out the side. So leave some space around your dehumidifier so that the vents aren’t obstructed, keeping the unit at least a foot away from walls and furniture.
- Close all windows and doors. Enclosing your space will help keep humid air from entering your home, allowing your dehumidifier to work more efficiently.
- Locate away from sources of dust and dirt (like woodworking equipment), which can clog coils and grills.
Maintenance Tips
- Empty the tank regularly. All dehumidifiers have an indicator that lights up when the tank is full, and the unit shuts off automatically. You can either empty the tank yourself or connect a hose to divert the water to a drain nearby.
- Clean the filter regularly. Filters should be washed and dried according to the manual’s advice to maintain efficiency. Many models have an indicator light that tells you when it’s time to clean the filter.
- Sanitize the tank weekly. A dehumidifier that’s not thoroughly cleaned can breed mold spores harmful to people with allergies. CR recommends doing a deep cleaning and sanitizing of the emptied tank at least once a week.
Best Practices for Reducing Humidity
Reducing sources of moisture can reduce your need for dehumidification. Here are some practical steps:
- Improve drainage around the foundation of your home to decrease humidity in your basement.
- Ensure that clothes dryers are properly vented to the outdoors.
- Use vent fans in bathrooms and kitchens to remove humidity at the source.
- Repair leaking outdoor faucets to save water and reduce humidity.
- If your home uses central air conditioning, consider installing an A/C vent in the humid space to take advantage of the dehumidifying capabilities of your A/C system.
Best Dehumidifier Recommendations
Based on performance, reliability, and user reviews, here are some top dehumidifier recommendations available on Amazon:
- Midea 50 Pint Cube: This Energy Star-rated model is praised for its large drainage bucket and quiet operation. Perfect for large spaces. Shop on Amazon
- Frigidaire Gallery FGAC5045W1: Features Wi-Fi connectivity for remote monitoring, ideal for out-of-the-way areas. Shop on Amazon
- Honeywell TP50WKN: A reliable choice for medium-sized rooms with a user-friendly interface. Shop on Amazon
Frequently Asked Questions (FAQs)
1. How do I know if I need a dehumidifier?
You might need a dehumidifier if you notice musty odors, condensation on windows, or frequent allergy flare-ups. A hygrometer can measure humidity levels; if it’s consistently above 50%, a dehumidifier can help.
2. What size dehumidifier should I buy?
The size depends on the square footage and moisture level of the space. For a 500-square-foot room, a 10-12 pint dehumidifier is sufficient for mild dampness. Add 4-5 pints for every additional 500 square feet or higher humidity.
3. Can a dehumidifier replace an air conditioner?
No, while both remove moisture, air conditioners primarily cool the air. Dehumidifiers focus on reducing humidity without significantly lowering the temperature.
4. How often should I clean my dehumidifier?
Clean the filter every 1-2 months and sanitize the water tank weekly to prevent mold and bacteria buildup.
5. Are dehumidifiers energy-efficient?
ENERGY STAR-certified models use about 14% less energy than standard units. Setting the humidistat to 50% and running the unit only when needed can further save energy.
Additional Resources
For more information on maintaining indoor air quality, check out these authoritative resources: