What Does A Dehumidifier Do?

If you often notice condensation on your windows, or have black patches on your walls, or your home has that musty smell, you might benefit from a dehumidifier. A dehumidifier is designed to keep the humidity at a comfortable level, as a result of which you’ll notice less condensation and mould and the room will smell fresher too. The best dehumidifiers are easy to use, energy-efficient , and able to work in a wide range of temperatures.

How Does A Dehumidifier Work?

A dehumidifier is designed to remove moisture from the air, this helps to eliminate condensation, reduce dampness on walls, and prevent the black patches caused by mould growth. There are 2 main types of dehumidifier, and they are best suited for different conditions. Let’s have a closer look at both types and see which is best suited for your situation.

Compressor (Or Refrigerant) Dehumidifiers

These work by drawing air in through a filter, the air then passes over cold coils, where moisture in the air condenses on the coils and drips into the tank. The dried air is then pushed out the opposite side of the machine by the motion of the fan. This dried air often feels warmer than the room temperature, mainly because damp air feels cooler than dry air.

Compressor dehumidifiers work best in heated rooms because they rely on the air being warmer than the cold coils so that evaporation can occur. If the room gets too cold, the coils in the dehumidifier may start to freeze. The unit will then have to go into defrost mode, wasting time and energy which could be spent removing moisture.

Desiccant Dehumidifiers

This type works by drawing moist air in through a filter, which is then trapped on an absorbent material and is then subjected to heat from a heat exchanger. The water drips into a tank and any water left in the absorbent rotor is dried out and pushed from the unit.

Desiccant dehumidifiers are not dependent on the room temperature to work, this makes them much more suited to colder rooms. Like Basements, garages or unheated conservatories. They use more energy than compressor models because of the heat they create to warm the absorbent rotor. They also pump out more heat which is not always welcome depending on where the dehumidifier is being used.

When Should A Dehumidifier Be Used?

Open Window

Dehumidifiers can be used in any season, they are particularly useful on hot, humid days in summer when opening a window just lets more humid air in. They will be useful:

  • After flooding
    Or if your home received flood damage in the past that hasn’t been dealt with properly.
  • To clear condensation
    If your windows often get condensation a dehumidifier will help to dry the moisture from the air.
  • Keeping mould and mildew in check
    Black stains on walls or ceilings is a sure sign of mould growth. This in turn is a sure sign of damp conditions. This is particularly prevalent in bathrooms or shower rooms and kitchens.
  • To prevent window sills from rotting
    Window sills are usually made from wood, if wood is subject to constant moisture, it is likely to rot.

How To Use A Dehumidifier?

Before operating your dehumidifier, be sure to vacuum the room first, this will prevent the filter getting clogged and also stop dust from flying around the room. Position the unit as far from any obstacles (like furniture or curtains for example) as possible. Always keep the doors and any windows shut in the room you’re dehumidifying, otherwise it’ll be working twice as hard to remove moisture from a much larger area.

You should try to maintain a humidity of between 45 to 60% for comfort. Remember to empty the tank regularly, and at least after every use. Be sure the tank is dry before storing the machine away to prevent any mildew or mould growth due to excessive moisture.

Be sure to inspect the filter regularly, these can usually be vacuumed or washed but check the manufacturers handbook before attempting to remove the filter. A blocked filter is the second main cause of operation failure, the top cause is the water tank is full.

What Are The Benefits Of A Dehumidifier?

There are many benefits for owning and using a dehumidifier, some more obvious than others. Here are the main benefits for owning a dehumidifier in no particular order.

  • Prevent mould
    Moist, damp conditions are ideal breeding ground for mould spores to form. They thrive in humidity levels of around 60 to 65% and above, and can cause damage to property and the infrastructure of the building. Mould spores are also responsible for aggravating several health conditions including skin rashes, eye irritations, sneezing, and asthma.
  • Prevent dust mites
    Dust mites thrive in moist, damp conditions, improve the conditions and eradicate the dust mites. Dust mites also cause allergic reactions in people and are especially bad for asthmatics.
  • Improved air quality
    Less moisture in the air means higher oxygen levels, this makes the air easier to breathe, and no amount of air purifiers will do any good if the air is too damp.
  • Portable – Easy to move from room to room
    Dehumidifiers are easy to carry from room to room allowing you to target damp anywhere in the home. Some even have low-temperature options for use in basements etc. There are also models fitted with wheels for ease of portability.
  • Reasonably priced
    As with most appliances there are many price variations, but there are many makes and models to choose from and many make budget priced models too. Look into this properly though, and be sure to purchase the model that best suits your needs.
  • Energy-efficient
    Many models have energy saving features like automatic shut-off when the humidity reaches the preset level. They also shut off when the water tank is full preventing any flooding or water spillage. Some have an auto-defrost feature, this allows you to use the dehumidifier in colder conditions without worrying about frost damage.
  • Sizes to suit any space
    There are small, mid-sized and large models that will have different water tank sizes depending on the model. Choose a 25 to 40 pint capacity for use in small rooms, a 40 to 59 pint capacity for medium sized rooms and a 60 and over pint capacity for large rooms.
  • Easy maintenance
    Apart from emptying the water tank, the only other maintenance required is to remove, clean and replace the filter occasionally.
  • Drainage hose
    Many models have the facility to fit a drainage hose to the water tank to allow continuous usage without having to empty the tank. This can be particularly useful in heavily moisture-filled rooms. The drainage hose is connected to the water tank and allowed to drain via a drain, sink etc.
  • Relatively quiet
    When in operation, dehumidifiers are usually quiet, this allows you to get on with your life in comfort while the dehumidifier is removing moisture from the air.

How Much Water Should A Dehumidifier Collect In A Day?

How much water a dehumidifier can collect is subject to how much moisture is in the air, how big the reservoir is, how large the area is, and how often you empty it. Most manufacturers claim that a dehumidifier can collect between 2 and 4 gallons per day for a small unit. And up to 10 gallons for large models. 

But you need to take into account:

  •  How damp the room is
    If it’s not very damp, the dehumidifier will not be able to remove as much moisture. 
  • Room size
    A small room will contain less moisture than a larger room.
  • Temperature
    This is definitely a factor, more so for refrigerant (compressor) models, if the temperature drops below 19C (66 F) they extract less as they begin to form ice.
  • How often you empty the reservoir
    Once the water reservoir fills up, the unit will cut out, and will only restart once the tank is empty again.
  • Capacity
    As we said earlier different models have different capacities for water. The larger models have the capacity for over 60 gallons, whereas the smallest units only have the capacity for 25 pints.

Frequently Asked Questions

How do you know if you need a dehumidifier or humidifier?

You know you need a dehumidifier if your home has more than 50%humidity. If the humidity is below 30% you need a humidifier.

Does a dehumidifier help with mould?

A dehumidifier does help with mould. It does not kill mould but by lowering the humidity you can prevent mould spores from spreading.

Can a dehumidifier cool a room?

A dehumidifier can cool a room by taking the moisture away. This leaves the room feeling less sticky and damp.

Are dehumidifiers worth it?

Dehumidifiers are worth it if your home suffers from damp, mould, mildew, dust mites, or if you suffer from allergies or asthma.

Will mould die if it dries out?

Mould will not die if it dries out, it just becomes dormant. It will regrow as soon as conditions are favourable for it to grow again.

Do dehumidifiers use a lot of electricity?

Dehumidifiers don’t use a lot of electricity.  An average dehumidifier uses about the same electricity as a computer, and far less than a water heater, air conditioner or a hair dryer.

How long should I leave a dehumidifier on for?

You should leave your dehumidifier on for as long as it takes to remove excess moisture from the room. This is usually around 12 hours.

Are dehumidifiers good for your health?

Dehumidifiers are good for your health because they remove moisture, mould spores, dust, and mildew. All of which can cause allergies and exacerbate asthma.

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