Dehumidifiers Buying Guide

We all require optimal, healthy levels of moisture in our homes and office spaces. Too much moisture in the air will typically cause condensation on windows and damp. Excess water vapour can also permeate through walls, furnishings and clothes - creating expensive damage associated with mould, rot and peeling wallpaper and paint.

Harmful dust mites thrive in high humidity. As do some bacteria. Ideal moisture levels are around 45%. Much over 60% and you will benefit from the use of a dehumidifier to create a comfortable and safe environment.

What does a dehumidifier do?

A dehumidifier is the perfect tool to protect any space from mould and condensation which can also help you prevent and get rid of damp. They remove the excess moisture in the air which lead to these problems in the first place by controlling the relative humidity of a room which should be around 40-50% for optimum levels.

Cooking in the kitchen, taking baths or showers, drying laundry and even breathing all create moisture.

When the amount of moisture in the air rises above optimum levels it can start to cause problems. When this trapped excess moisture has nowhere to go, condensation starts to occur.

During the colder months, the drop in temperature causes this moisture to condense on cold surface areas such as windows, walls and tiles. If left untreated for certain periods of time, damp and mould start to thrive.

A dehumidifiers job is to maintain the relative humidity of its environment by drawing in moist air, removing the excess moisture, then re-releasing the regulated air back out again.

Using a dehumidifier regularly will keep its environment free from damp, mould and the musty smell that often comes along with it.

How does a dehumidifier work?

At a basic level, all dehumidifiers follow the same process. As mentioned previously, they start by drawing in moist air from the surrounding environment, extracting the excess moisture and then pumping the regulated air back out again.

This is how dehumidifiers work at a base level. There are, however, two main unit types for extracting moisture from the air – Compressor Dehumidifiers and Desiccant Dehumidifiers.

Compressor - Moist air is drawn in which then passes over a set of coils which are made cold due to the refrigerant in the unit. The coils cool the warm moist air and re-release the regulated air back out again. Any excess moisture is collected in the unit’s internal water tank or drained via a continuous drainage system.

Most compressor dehumidifiers also have a heating coil which allows the cool air to pass over it preventing the dehumidifier causing the room to get cold. Many also have either a HEPA or Anti-Bacterial filter to remove dust and allergens from the air before it is re-released back out.

Desiccant – uses a completely different method to extract moist air. Instead of using a refrigerant to cool coils, a desiccant dehumidifier uses a desiccant material, typically zeolite in a moisture absorbing desiccant wheel to soak up excess moisture. A heater in the unit then raises the temperature of the desiccant wheel, causing the water to be collected in the unit’s internal water tank or drained via a continuous drainage system.

A desiccant dehumidifier is on average quieter and lighter than a refrigerant dehumidifier due to the fact it does not have a compressor. The air that is warmed in the unit also allows a desiccant dehumidifier to act as a mild heater.

Which Dehumidifier Do I Need?

Compressor dehumidifiers are the most commonly used home dehumidifiers. They are best suited in environments with temperatures at 16° and higher. Compressor dehumidifiers do not work in temperatures below 16° because the coils inside the unit start to freeze over which triggers a defrosting program. The lower the temperature drops, the more time the unit spends working to defrost the coils rather than dehumidify the environment.

Desiccant dehumidifiers on the other hand can provide a more constant consistent performance due to their lack of a refrigerant and coils and are effective in cooler conditions below 15° as well as above. This makes them perfect for conservatories, boats and caravans. The main disadvantage to desiccant dehumidifiers however is their greater energy consumption and running costs due to their method of extracting moisture.

In short, compressor dehumidifiers are best suited in warmer conditions above 16°. They are unable to extract any moisture of the air in conditions below 16° and waste energy attempting.

Desiccant dehumidifiers use more energy however, they always work at their optimum level regardless of temperature.

Other Important Considerations

When looking at dehumidifiers, it is important to look at the size of the environment. The larger the environment, the more powerful the dehumidifier needed.

Most dehumidifiers can cope with the moisture created by cooking and showering, but extra moisture caused by drying laundry, using paraffin heaters or having pets and plants will also need to be accounted for when selecting a dehumidifier.

Indoor pools will require specialist Swimming Pool dehumidifiers which must have low voltage controls to provide electrical safety in a wet environment and have specially coated coils to protect them from the chemicals that are to be found within a swimming pool environment.

A standard dehumidifier will not work in a swimming pool environment because it will not be able to cope with all the excess moisture. If a specialist dehumidifier is not used, it can have a devasting effect on the internal structure of the building causing mould to grow wherever there are cold patches and paint to peel away from the walls. Windows will also be covered in condensation and the room air will be more expensive to heat.

If there is flooding or burst pipes, then a building dryer dehumidifier will need to be used. Building dryer dehumidifiers are used to dry damp buildings quickly and effectively. They are also used to dehumidify the air to reduce condensation after building work, plastering or decorating.

Another extremely important factor with dehumidifiers is where the unit is placed in the environment. Providing the dehumidifier is correctly powered to tackle all the moisture, the centre of the room is always the best place. For example, a hallway or landing would be the perfect place to put a dehumidifier in a home to ensure it covers both upstairs and downstairs.

However, if there is a problem in a specific area, it is recommended to place the dehumidifier close to that specific area for a couple of weeks before moving it to a central position.

Compressor Dehumidifiers

Compressor Dehumidifiers

Desiccant Dehumidifiers

Desiccant Dehumidifiers

Swimming Pool Dehumidifiers

Swimming Pool Dehumidifiers

Commercial Dehumidifiers

Commercial Dehumidifiers

Dehumidifier Feature FAQs

Daily Extraction Rate (L) – is how dehumidifiers are measured. As the name suggests, the daily extraction rate is how much water the unit can extract in 24 hours. A higher litre size will mean a higher daily extraction rate.

(*As a benchmark, the daily extraction rate of Meaco dehumidifier units will be measured at 30°C room temperature with 80° relative humidity. These numbers can vary slightly between brands so it is important to check the daily extraction rate of the unit against the circumstances the unit is needed for to ensure the dehumidifier is adequately powered.)

Tank Capacity (L) – refers to how much water the dehumidifier can hold in its internal water tank once its been extracted from the air. The larger the tank, the less it will need emptying. However, a continuous drainage system will allow the unit to continuously drain the water to save the hassle of constantly emptying the tank.

Power Output (W) – is how much power the unit uses. This will also help you understand how much the unit will cost to run.

Humidistat – premium feature which allows a dehumidifier to monitor and work towards a target humidity and moisture level in the air.

The unit will automatically turn on once it detects the humidity and moisture levels are sub-optimal. Once the desired levels have been reached, the unit will automatically turn off.

The feature allows the user to save their ideal settings, reduces the need to micro mange the unit and also saves energy.

Noise Level (dB) – refers to how loud a dehumidifier is.

It is important to think about where the unit will be placed and if the noise will be a problem. For example, a dehumidifier with a relatively high noise level may not be the best option if it is placed in the living room of a home. Whereas, the noise level of a dehumidifier may not matter too much if the unit is placed in a garage.

Automatic Shut Off – is when the unit will automatically shut down if the internal water tank is in danger of overflowing. Many dehumidifiers also have indicator lights to show when the tank is full or nearing full.

Automatic Restart Function – is when the unit will automatically restart if the power goes off. This is useful if the dehumidifier will be left alone for long periods of time.

Laundry Mode – is an additional feature which allows clothes to dry effectively and efficiently. In most cases, a dehumidifier with a laundry mode can dry your clothes far cheaper than a tumble dryer will do and there’s no need for the open window as there’s no excess heat produced.

The laundry mode increases the fan speed so the air in the room becomes drier. This allows the laundry to dry faster cutting down the time moisture is in the air.

Although this feature is not as powerful as an actual laundry/tumble drier, it will save much more energy.

Defrost Technology – During the colder months, a dehumidifier may be operating below freezing point which can cause the collected water inside the unit to freeze. If this happens, this function automatically defrosts the unit so that it can continue to work successfully. It also actively checks to ensure the mechanism is not freezing so that the components won’t break if the water does happen to freeze.

Ioniser – An ioniser purifies the air. They work by creating a static charge around harmful airborne particles which causes them to stick to the nearest surface the find.

Air Filtration – Many dehumidifiers come with either a dust or HEPA filter that purify the air.

Similar to an ioniser, an air filter will also purify the air. However, instead of causing the particles to stick to the nearest surface they can find, the filter will draw them in.

A dust filter will purify the air by collecting any dust particles. A HEPA (High Efficiency Particulate Air) filter will purify the air by collecting dust, pollen, spores, bacteria and various other particles.

These filters will need to be cleaned regularly and changed once they are worn down. We recommend that HEPA filters are changed once every six months. Your mileage my differ if you use your dehumidifier more heavily.

Carry Handles and Wheels – make it quicker and easier to transport the dehumidifier. This feature is especially welcome on compressor models due to the heavier nature of the components & mechanisms when compared to desiccant dehumidifiers.

At AirconCentre.co.uk, we pride ourselves on providing a quality range of dehumidifiers that from the best manufacturers at only the best prices. If you're unsure as to which Dehumidifier is right for you, you can use our LiveChat to speak to an expert, or if you prefer to speak to someone, our dedicated Customer Services team are on hand to assist. Call us on 0800 865 4567