Dehumidifier is an HVAC device that removes moisture from indoor air. Modern dehumidifiers can extract more than 100 pints of water from indoor per day. They are more capable of extracting over 100 pint of water per day from outdoor air. A refrigeration-based system uses refrigeration and heater-based systems to reduce relative air humidity from 50-100% to 30-50% of air.
A dehumidifier works to reduce humidity by:
- A dehumidifier works by drawing warm air currents into its coils via a fan.
- The warm air contracts as it's fed through the refrigerated coils of the dehumidifier.
- Water is then left inside the dehumidifier tank.
What does a home dehumidifier do?
A dehumidifier is a bit like a vacuum cleaner. It sucks in air from your room at one end, removes the moisture content, and blows it back out into the room again. The moisture drips through into a tank that you have to empty from time to time.
How does a dehumidifier work?
Dehumidifiers work in one of two ways: by using refrigeration or absorption. A dehumidifier will remove moisture by similar technology to that of a refrigerator or air conditioner.
How A Refrigeration Dehumidifier Works
As the moist air passes over a refrigerated coil, the cold evaporation process converts it into water vapor. Once cooled back down again, the now dehumidified and warm air is circulated around your room.
- Warm, moist air is sucked in through a grille on one side of the machine.
- Once the dehumidifier is running, an electric fan draws the air inward.
- Warm air flows over piping with coolant circulating inside of it. The moisture in this warm air turns into liquid water and drips downward off the pipes.
- When the air comes in contact with the condensers, it then warms back up and is ready to circulate back into your home.
- The warm, dry air is blowing back into the room through another grille.
- Water in the air gets into the machine. It goes down and collects at the bottom of it.
- The plastic float goes up as the collecting tray fills with water.
- When the condensate tray is full, an electric switch turns off the fan and turns on an indicator light telling you that the machine needs emptying.
How A Desiccant (Absorption) Dehumidifier Works
A desiccant, usually a dust-free solid that absorbs water (or some other liquid), is used to help keep an enclosed area dry.
Desiccant dehumidifiers are typically composed of a desiccant material which extracts moisture from the air and returns it to the reactivation air stream at high temperatures.
- The humid room air is drawn in from the duct.
- Air moves past a large rotating wheel of water-absorbant material, which removes the humidity.
- Air is pulled into the unit by a fan powered by an electric motor.
- The dry air is pushed back out into the room.
- An air duct at the bottom is kept hot by an electric heating element (yellow).
- The moisture-attracting wheel rotates in a heated area and hot air is continuously blown past it to remove the water.
- 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.
A dehumidifier may help reduce mold growth
Dehumidifiers can prevent mold growth and remove some of the spores that are already present, but they're not an effective means for getting rid of new or existing mold in your home. Professionals should be contacted to complete a comprehensive clean-up.
Dehumidifiers may help control asthma
Breathing in overly humid air can cause asthma, so it may be worth investing in a dehumidifier. Dehumidifiers are electrical appliances that remove water from the air, thus reducing dust and mites while bringing down humidity levels.
Dehumidifiers help reduce allergy symptoms
Dust mites need a relative humidity level of 65 percent Trusted Source to survive. Dehumidifying the air also controls mold growth. Dust mite needs 65 percent relative humidity to survive and procreate to have a chance of infecting them. Environmental allergens can cause symptoms such as: allergies and asthma.
Dehumidifiers may help reduce dust mites
Dehumidifiers are an effective way to reduce the problem of humidity inside homes, and can help control dust mites.
Putting Your Dehumidifier to Work:
- Set the humidity level to achieve your ideal percentage. Optimal levels range between 30 and 50%.
- Find the right spot.
- Shut all windows and doors to start in a closed space.
- Empty or replace the tank regularly.
- Clean your dehumidifier regularly.
Do you need a dehumidifier?
In a home, excessive humidity can cause wood to rot and weaken. Mold, fungus, and dust mites are also common in homes with high humidity. You can use a dehumidifier to help cut down on the amount of dust mites, mold, or fungus in your home. Mold needs only a little bit of moisture to grow, so you can avoid it by keeping the humidity under 50%. Dehumidifiers are a great way to remove excess moisture from your home.
Even if you don't have a dehumidifier, there are some things you can do to keep the humidity in your house at an even level. You can fix leaky plumbing and faucets, patch cracks in your foundation, and try to keep the gutters clean.
Choosing the right dehumidifier for your space
A dehumidifier can remove moisture from the air in many different rooms. No matter where you put it, the way it works will be the same. But what kind to get depends on what room you are putting it in and what temperature it would be there.
When trying to buy a dehumidifier, you want to think about how many pints of water the machine can remove from the air.
The capacity of a dehumidifier and the size you need
The guide from Energy Star is a helpful way to see which capacity of dehumidifier you need. The size and moisture levels in the space determine what kind of equipment will work best for your situation, with bigger or wetter spaces needing more heavy-duty units.
For a moderately damp room that feels damp and has only an unpleasant smell when there is humidity:
- 500 sq. ft.: 10-pint dehumidifier
- 1,500 sq. ft.: 18-pint dehumidifier
- 2,500 sq. ft.: 26-pint dehumidifier
For a very damp room (space is always damp, smells musty, and wet spots are showing on the floors and walls),
- 500 sq. ft.: 12-pint dehumidifier
- 1,500 sq. ft.: 22-pint dehumidifier
- 2,500 sq. ft.: 32-pint dehumidifier
The temperature of the space and how it affects a dehumidifier
If you need to dehumidify a space with an air temperature below 65 degrees, there are special features that can be helpful. These devices have anti-frost sensors which will cause the device to shut off temporarily when frost is detected so it doesn't accumulate on the condensing coils.
What kind of dehumidifier do I need for my basement?
A basic mechanical/refrigerant (compressor) dehumidifier may be what you need to keep your basement dry. If temperatures generally go below 65 degrees in your basement, it is a good idea to consider the anti-frost sensor mentioned above - frost can impair the performance of the unit by causing its compressor to turn on and off without really removing any moisture from air.
You should also look for models with hose attachment features; these allow you connect hoses and direct other ends toward drains or sump pumps so that once again, even if power outages occur due to freezing temps outside during wintertime months, this will not interfere with how well one's home stays free of humidity!
What dehumidifier should I use for an attic or crawlspace?
Most homes have an attic or a crawl space. These spaces can present challenges for removing humidity, but in order to prevent mold and wood rot it is crucial that they are dehumidified as well! A regular compressor dehumidifier might work best for large attics while smaller enclosed spaces need lower capacity machines if the latter can't reach an outlet with extension cord access. If you're tight on room there's no better option than using a desiccant instead of other methods like humidifiers or buckets which don't provide permanent relief from dampness after all!
What dehumidifier should I use for a bathroom?
A 30-pint dehumidifier is best used for a bathroom, provided you intend to use it in conjunction with a fan or ventilation.
Use a desiccant for small, enclosed spaces
Rather than a bulky and expensive dehumidifier, use desiccant to keep humidity low in enclosed spaces.
A desiccant is not very good in large spaces. But it could work in small, enclosed spaces where you need to control humidity.
What is humidity?
Humidity is the concentration of water molecules in the air. Water vapor, which can be seen as vapor or fog, usually cannot be seen with human eyes except when it condenses on cold surfaces.
Why does indoor humidity matter?
Humidity can cause moldy clothing, rusting computers and short circuits inside cases. The majority of adverse health effects caused by humidity would be minimized by maintaining indoor humidity between 40 and 60%.
Elevated humidity will encourage bacteria, fungi and viruses among other things. It is also capable of preventing mold on clothes, computers, optical equipment and binoculars for example.