What does a dehumidifier do, its pros and cons

What does a dehumidifier do, its pros and cons

Have you ever experienced that sticky, heavy feeling in the air that can make your skin feel damp and your clothes stick to you? That’s moisture, and it can cause all kinds of problems in your home, including mold growth, musty odors, and damage to furniture and other possessions. Fortunately, there’s a simple solution: a dehumidifier.A dehumidifier is a household appliance that works by drawing moist air from a room or enclosed space, passing it over a cooling coil that condenses the moisture, and then releasing the dry air back into the room. This helps control humidity levels, which can be especially important in high-humidity areas or during the humid summer months.

Dehumidifiers are often used in basements, bathrooms, laundry rooms, and other areas where moisture is common. They can also be helpful for people with allergies or respiratory problems, as high humidity levels can aggravate these conditions.If you’re thinking about getting a dehumidifier, you may be wondering how it works. Unlike humidifiers, which add moisture to the air when it’s too dry, dehumidifiers do the opposite by removing moisture from the air when it’s too humid. This makes them great for hot climates or anyone who wants a more comfortable living environment during the spring and summer.

Investing in a dehumidifier can have a big impact on your overall comfort and well-being, as well as the health of your home. By controlling humidity levels, you can prevent the growth of mold and mildew, reduce musty odors, and protect your furniture and possessions. So why not explore the benefits of using a dehumidifier and see if it’s the right choice for you?

Benefits of a Dehumidifier

1. Odor Buster

An excessively moist environment can be a breeding ground for mold and mildew. These organisms can not only look unsightly, but they can give off an unpleasant smell that can trigger asthma flare-ups and other reactions in sensitive individuals.

2. Stuff Protector

Mold and mildew can grow on walls, curtains, rugs, furniture and other household staples and easily ruin them. By keeping the environment too dry to encourage this growth, dehumidifiers help keep the items in your home free from damage.

3. Health Helper

Speaking of damage, mold and mildew can wreak havoc on certain people’s health. Allergies to the spores these substances produce can be as mild as watery eyes and running noses, to as severe as serious breathing difficulties. And even though a moist environment can keep dust particles from flying around the air, it can also help dust mites thrive, which can, again, lead to serious allergy complications. According to the Asthma and Allergy Foundation of America, dust mites do best in higher humidity levels of between 70% and 80%.

4. Pest Repeller

In addition to keeping dust mites at bay, a dehumidifier can keep away other pests like termites, earwigs, centipedes and roaches. Like all life, these insects need moisture to survive, and if they can’t find it in your home, they’ll move on to search for it elsewhere.

5. Lower Energy Costs

When your air conditioners run, they work by removing moisture from the air before they can deliver their cooling currents. If your home is excessively humid, the AC units will have to work even harder to get the job done and, as a result, can run up your electric bill. Letting an AC system and dehumidifier work in tandem and cut power costs over the long run.

With many great dehumidifiers coming in under a $500 (CAD 650) price tag and costing less than about 10 cents an hour to run, if you have a moisture problem in your home, adding one or more to the most problematic rooms is an investment that will pay dividends by warding off potential damage to your house and your health.[1]12 Benefits a Dehumidifier

How does a dehumidifier work?

Dehumidifiers work in one of two ways—by 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). We’ll look at each of these in turn.[2]How does a dehumidifier work?

what does a dehumidifier do


  • Warm, moist air is sucked in through a grille on one side of the machine.
  • An electric fan draws the air inward.
  • The warm air passes over freezing cold pipes through which a coolant circulates. (Note: We’ve simplified this part of the machine quite a lot. It’s like a mini air-conditioner or refrigerator endlessly circulating coolant with a pump and compressor.) As the air cools, the moisture it contains turns back into liquid water and drips downward off the pipes.
  • Now free of moisture, the air passes over the hot condensor/compressor unit and warms back up to its original temperature.
  • Warm, dry air blows back into the room through another grille.
  • The moisture that was in the air originally drips down into a collecting tray (or bucket) at the bottom of the machine.
  • A plastic float in the machine rises upward as the collecting tray fills up.
  • When the tray is full, the float trips an electric switch that turns off the fan and switches on an indicator light telling you the machine needs emptying.


Not all dehumidifiers work by refrigeration. Some work by “mopping” the water out of the air with a water-holding material and then “squeezing” the water away to remove it. The mopping action involves either absorption (where the water soaks right into something) or adsorption (where the water is picked up on the surface of something).

what does a dehumidifier do

I haven’t been able to discover if there was an original inventor of the dehumidifier—someone who first came up with the idea of removing water from air with a machine—or if the idea evolved gradually over time. Willis Carrier, pioneer of the air conditioner, is certainly one strong candidate; his machines were largely based on refrigeration technology and, although described as “air conditioners,” could remove moisture from air too. Another early contender is James Locke, who produced this ingenious absorption dehumidifier and air conditioner for Honeywell in 1939/1940. I’ve colored it in and picked out a few of the key components to illustrate the basic principle, but I’m going to gloss over the details.

How does it work?

  • Moist air is drawn in from the room through a duct.
  • The air moves past a large rotating wheel made of water-absorbing material, which removes the humidity.
  • The air is drawn by a fan operated by an electric motor.
  • Dry air is blown back out into the room.
  • An air duct underneath is kept hot by an electric heating element (yellow).
  • The moisture-absorbing wheel rotates through the heated air space and has hot air blown past it to dry it out.
  • The air is sucked past by a fan and electric motor similar to the one up above.
  • The hot, wet air is blown out through an exhaust duct.

What Are Some Dehumidifier Advantages?

A dehumidifier can reduce the overall humidity level in your home, which may make your home more comfortable and reduce symptoms of allergies and respiratory illnesses. Here are some dehumidifier pros to keep in mind.[3]Dehumidifier Advantages and Disadvantages

Helps With Allergies

Excess moisture in the air promotes mildew and mold growth, and mold spores cause allergy symptoms in many people. Individuals who suffer from dust allergies can also benefit from an environment that is lower in humidity since dust mites — the reason for dust allergies — need between 60 and 80 percent relative humidity to thrive. Running a dehumidifier can reduce the relative humidity in your home to 50 percent or lower. Eliminating problems with dust mites and mold in your home may result in better health and less reliance on allergy medications.

Increases Comfort

If you had to choose between being in a room that is 80 degrees and 90 percent humidity or a room that is 80 degrees and 50 percent humidity, chances are you’d choose the latter. Lower humidity can help you feel more comfortable, even when temperatures are high, as sweat evaporates more easily from your body in drier air. You may be comfortable keeping your thermostat a few degrees higher in the summer, which can save you money on your energy bill.

What Are Some Dehumidifier Disadvantages?

While dehumidifiers can improve the indoor air quality in your home, they are not right for everyone. Here are some dehumidifier disadvantages that homeowners should be aware of before purchasing one of these appliances.

Noise and Heat

Depending on the type of dehumidifier you have, they can be surprisingly loud. This noise isn’t usually a problem if the dehumidifier is located in a basement, but if you plan to place a dehumidifier in a living space or bedroom, select a model that’s quiet enough for those environments. Dehumidifiers also tend to blow warm air out of the back of the unit. While the amount of heat typically is minimal, you can keep it out of the room you’re in by facing the back of the dehumidifier into a doorway.

May Increase Your Energy Bill

If you use a dehumidifier to lower the moisture level in your home, your monthly energy costs may go up by over $50, although an increase of $15 to $35 is more typical. Fortunately, you are likely to incur these additional electricity costs only during the summer unless you live in an area that is warm year-round, such as south Florida. You can reduce the amount you spend to run the dehumidifier by purchasing an energy-efficient Energy Star model, which will have little effect on your electricity bill.

Requires Regular Maintenance

Dehumidifiers collect water in a storage tank that must be routinely emptied and cleaned as often as once daily or more during damp weather conditions. Some models also feature a removable air filter that must be cleaned regularly. On many dehumidifiers, you can reduce your maintenance requirements by installing a drain hose that empties collected water into a floor-level drain.

7 Health Benefits Of Having A Dehumidifier At Home

A dehumidifier is one of the appliances that reduces moisture in the air by removing water to improve indoor air quality. Being able to control your homes’ air condition is very important for your health because excessive humidity is harmful to your health and home.

Humidity is expected during the spring and summer seasons when there is a lot of moisture in the air. According to one of the researchers, the recommended humidity level should be between 40%- 60%, making most homes in America use dehumidifiers. According to the new technology, dehumidifiers are made quieter, more compact, and are less expensive. Other than dehumidifiers, there are different ways to prevent air pollution in the room.[4]7 Health Benefits Of Having A Dehumidifier At Home

Here are some health benefits of having a dehumidifier at home:

1. Combats Mold And Mildew

Mold and mildew growth happens when there is excessive moisture in the air. Mildew grows on the surface, while mold can penetrate and grow beneath the surface of your house items. Observe them on your pipes, ceiling, windows, wood, paper, carpet, wallpaper, and drywall.

Mold and mildew are the root cause of various health-associated problems such as breathing difficulties like asthma and allergy, wheezing, irritation, and more. The fungus has been reported to cause depression and disorders in the nervous system.

While trying to fix your air conditioners and leaky faucets to prevent water from increasing the level of humidity in the house, it’s a good idea that will only help you in the short run. It also means it’s time to get the best dehumidifier you can find to solve your problem in the long run.

2. Go From Damper To Drier

A home is a warm, cozy place and the last thing you’ll want to experience is dampness and an uncomfortable environment. Moisture in the air is the worst that exists, as air can dampen anything that gets in contact with and won’t choose your favorites, from expensive households to your books, and more so your health.Dampness causes respiratory infections allergies and can also affect the immune system. Well, that’s why dehumidifiers are used to prevent and protect your home from harm from excessive moisture.

3. Getting Rid Of Musty Smells

A musty smell is an aftermath of excessive moisture, which raises the growth of mold and mildew. These fungi are known to release foul gases absorbed by your home’s households like furniture, carpet, walls, and any fabrics.However, a dehumidifier can absorb the excessive moisture in the air, making your home as comfortable and friendly as it should be.

4. Less Risk For Virus Spreading

Maintaining your indoor humidity between 40%- 60% would help reduce the viruses in the air you breathe. Viruses spread quickly in moist environments, hence risking your health condition.Home dehumidifiers drastically reduce the risk of viruses and the growth of mold spores that lead to health problems.

5. Healthier Skin, Scalp, And Hair

Humidity levels are significant for maintaining healthier skin, scalp, and hair. If your hair has increased dandruff and your scalp is always dry in the winter seasons, or you feel your skin is not adequately hydrated, your moisture level at home might be the cause.A home dehumidifier will ensure the humidity level in the house is at the right level, falling within a healthy range.

6. Improve Respiratory Issues

Too much moisture in the air causes difficulty in breathing. High humidity also increases mold growth and dust mites, which can trigger respiratory issues. Humidity and asthma don’t get along. It tends to worsen symptoms.Dehumidifiers reduce the level of moisture in the house, making the air in your space more comfortable to breathe.

7. Reduce Dust Mites

A healthy benefit of having a dehumidifier is that it can help reduce dust in your space. When a dehumidifier reduces the amount of air, dust mites and bacteria can no longer spread.A dehumidifier is powerful enough to filter out dust floating in the air. Dust in the atmosphere leads to congestion and a sore throat. When the humidity level is not within the desired range, individuals frequently complain of headaches and allergies.


Controlling the humidity in your home can be a challenge. Both high and low humidity levels can cause discomfort and possibly lead to some serious health issues.

Dehumidifiers are used when humidity levels are high to remove excess moisture in the air. They help manage humidity during sticky summers and in damp rooms like basements, crawl spaces, and garages. Some homes may only experience moisture issues at certain times of the year, while others need to control them year-round.[5]When to use a dehumidifier

Dehumidifier Frequently Asked Questions

What does a dehumidifier do?

A dehumidifier removes water from the air in your home until relative humidity is reduced to the level you choose. Once it has reached this level a good dehumidifier should automatically maintain that comfortable level with no interference from you!

What is relative humidity?

Relative humidity is a measure of how much water is in the air relative to the amount that air could hold if it was saturated. Relative humidity is expressed as a percentage. When relative humidity reaches 100% it is at the “dew point”. In other words the air is “full” of water and that water will start to condense onto any surface. Warm air holds more water than cool air so as air cools relative humidity rises even though the physical quantity remains constant.

For every fall in temperature of 20°F/10°C the capacity of the air to hold water is halved. For example air at 80°F with a relative humidity of 50% will reach the dew point, 100% RH when it has cooled to 60°F.[6]What is relative humidity?

Where does the water come from?

Water is always in the air, inside and outside the home. The amount inside the home varies and is increased by many routine daily life activities such as cooking, washing, showering, making tea and breathing. If you have uncovered water containers in the home like fish tanks etc, then these will also add to the amount of water in the air.

What is the ideal humidity level for my home?

Generally a relative humidity of 50% is comfortable for your home. This will protect your home and belongings, prevent mold growth and control the dust mite population. There is no real need to reduce humidity below the 45-50% mark. To do so will simply cost more in energy while serving no useful purpose.[7]Three Signs Your Home Has Poor Indoor Humidity

How long will it take to get the moisture under control?

As long as the dehumidifier you choose is large enough for the area it is working in, and there are no specific damp problems, then a dehumidifier will normally reduce the humidity to the chosen level within a few days to a week. This timescale does not apply if the room has been flooded, in which case one or more dehumidifiers will be needed and possibly supplemented by air movers and other specialist equipment. This work is usually undertaken by specialised water damage specialists.

How much water does a dehumidifier remove?

The answer to this depends on three specific factors. The power of the dehumidifier, the room temperature and also the relative humidity of the air in that room. A 12 litre dehumidifier will rarely, if ever, remove 12 litres in a single 24 hour period. Once relative humidity has been reduced to your chosen level the dehumidifier should only be operating intermittently to maintain that level so the amount of water collected in the bucket will be lower still.

As a general rule of thumb you may need to empty your dehumidifiers bucket at intervals ranging from once every two days to twice a day, depending on the conditions. It is only in exceptional circumstamces that a properly sized dehumidifier will need emptying more frequently than this, unless of course you have placed it in a very damp room for the first time.[8]How much moisture does a dehumidifier remove?

Can I use the water that collects in the bucket?

The water collected in the dehumidifiers tank is called condensate, you can use this in your iron or to water the plants! However, it should not be drunk by humans or animals as it may contain traces of substances that could make you, your pets ill.

How do I know how big a dehumidifier I need?

This is basically down to the size of the room and how wet it is. But in general you will find most dehumidifiers on our site are classed by house size to make the job easier for you to choose. For instance our smallest dehumidifiers are ideal for anything up to a 3 bedroom house. Our larger units are ideal for homes with up to 5 bedrooms. In general terms we would always recommend that you err on the side of caution and if in any doubt buy a dehumidifier a size larger than you may appear to need. Larger dehumidifiers remove more water per energy pound spent and run for fewer hours in a given space than smaller ones. The energy saving will almost certainly be greater than the difference in purchase price.[9]How to Choose the Size of a Dehumidifier

How does a dehumidifier prevent mold and mildew?

A dehumidifier prevents mould and mildew growth in two ways. First it dries out the room, drawing damp from the contents and fabric of the room on which mould and mildew will inevitably form and prevents that damp from recurring. Secondly, providing the dehumidifier is set to maintain relative humidity at 50% or slightly below, the air is too dry for mold and mildew spores to develop. Fungi need airborne water as well as surface water to grow![10]Do dehumidifiers help with mold?

Where is the best place to site my dehumidifier?

In an ideal world a dehumidifier would be silent and invisible. The next best thing is to be out of sight and earshot. Unfortunately the first is impossible and the second, while achievable in some cases, be more expensive in cost and effort. If you need to lower humidity throughout your house a whole-house dehumidifier is the best option. It is easy to fit, virtually silent and is the cheapest solution for whole house control. If you are using a portable dehumidifier in a small to medium sized room, a laundry room or a bedroom for example, it is not particularly important where you position it.

What is Continuous Drainage?

All portable dehumidifiers have a water collection container, often called a tank or a bucket, to collect the water extracted from the air. These buckets are quite small, to keep the overall size of the dehumidifier down, and need to be emptied at least once a day. Because it may not be convenient, or possible, to empty the bucket daily almost all portable dehumidifiers for home use are designed to allow the water to be drained directly as it is collected. This is known as continuous drainage. In the casing of the dehumidifier a small hole has been cut to allow a small hose ( most of our units come with this hose in the box ) to be attached to the dehumidifier through which the water can be drained. The water is drained by gravity alone so for effective continuous drainage the dehumidifier needs to be raised a foot or two above the floor and the hose run to a floor level drain.

Is it good to sleep with a dehumidifier?

Yes it is perfectly safe to sleep in the same room as a dehumidifier. If you are particularly interested in a dehumidifier for the bedroom the noise level will be particularly important to you.[11]Do you sleep better with a dehumidifier?

Which is better air purifier or dehumidifier?

If you’re hoping to reduce mold, mildew and moisture, a dehumidifier is your best choice. However, if allergy control and air quality are top priorities, a convenient air purifier is undoubtedly the way to go.[12]Dehumidifier vs air purifier: What’s the difference?

Does dehumidifier remove smell?

There’s a musty smell in your home

When you walk into your home, you want it to smell clean and fresh. Moisture in the air tends to hold and trap odor, Bautista says. A dehumidifier will dry out the air and take away this moldy scent.[13]How to Remove Smells With a Dehumidifier

Do dehumidifiers remove mold?

Mould will easily grow and spread if the right conditions are present. So, dehumidifiers don’t kill mould, but they can help to prevent it from growing inside your home by reducing humidity.

Do dehumidifiers clean the air?

Definitely not. As their names suggest, a dehumidifier pulls moisture from the air while an air purifier cleans the air. Both can mitigate the health effects of allergens and contaminants but do so in very different ways.[14]Can a Dehumidifier Improve Indoor Air Quality?

Are dehumidifiers worth it?

Are dehumidifiers worth it? Yes, if you’ve got damp problems. Broadly speaking, cheaper models have fewer features, a smaller tank capacity and may not be as efficient at water removal. Pricier models typically have a better water-removal capability, higher energy efficiency, more features and a larger tank capacity.

About De Hua

De Hua is a former New Yorker who now lives at the beach. She received a double B.A. in International Relations and Marketing from The College of William & Mary and an M.A. in Interactive Journalism from American University. De Hua has been published in The Washington Post, New York Daily News, Cosmopolitan, Women's Health, The Bump, and Yahoo, among others.How We Tested and Reviewed

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