A dehumidifier is a device that helps to remove excess humidity from the air and improve air quality.

Ideal for anyone who suffers from condensation problems, house dehumidifiers can help prevent allergy triggers like dust mites, mildew and mould growth around the house, while also preventing damage to furniture and other household items. A typical unit will contain a large tank that's placed in a room or area of your home where there's likely to be high levels of moisture damage, e.g., near an indoor pool or laundry room.

As the machine operates, it sucks up humid air from its surroundings and the warm air passes through a compressor. As the air cools, the air turns into cold liquid water which then drips down into the collection tank below. Once full, simply collect water by opening the tank and pouring it down your sink. Desiccant dehumidifiers have silica gel which helps in better absorption of moisture. The dehumidifier somewhat works like air conditioners, converting wet air into dry air similar to air conditioning.

Depending on the size of your living space, you may need a dehumidifier per room or possibly just one centralised whole-house machine that covers every area. For a large country house that contains a pool room, double garage and several other areas where indoor humidity are likely to be high, a large single-model suited to an entire property will be required.

If you're living in a small flat with little space for bulky items, it makes sense to use the smaller portable dehumidifiers as needed around the home. In any case, make sure there's easy access to emptying/filling as part of your decision process.

When should you use a dehumidifier?

If you live in a humid climate, or if you have an indoor swimming pool or steam sauna in your home, then there's likely to be high levels of moisture in the air in your home much of the time. This water vapour can cause problems with condensation and mould growth on walls, ceilings and floors around the house. A dehumidifier works to help reduce this problem by extracting the excess collected water from damp/wet areas before it has a chance to damage walls or other surfaces. A dehumidifier is very useful for areas that experience damage due to various natural disasters like rainfall, etc. After heavy rainfall, if water leakage is a problem then dehumidifiers are useful for the drying process of this excess water. Although it's less common for smaller homes, excessive humidity can also be caused by an ill-maintained central heating system that leaks moist air into your property at all times of the year. It could even result from faulty extractor fans which pull too much indoor air into your kitchen or bathroom, causing the moisture levels to rise. Whatever its cause, dehumidifiers work in all of these scenarios for successful humidity control and improved fresh air . There are three main types of machines available, listed below.

  • Freestanding console units designed to sit in a single area and remove excess water from the vicinity.

  • Portable dehumidifier wands are hand-held devices that can be moved around a house or dragged along walls/ceilings to reach hard-to-reach areas where there's dampness/condensation present.

  • Centralised whole home machines are much larger than traditional freestanding models, they help keep excess humidity under control across your entire property 24 hours a day, 365 days a year.

What should you consider when buying a dehumidifier?

Take a look below at the common considerations when buying a humidifier.

Capacity

The amount of water your machine can extract from the air in one day will depend on its size. If you live in a relatively small home then anything around 30-50L capacity per day should be sufficient, but if you have an outdoor pool or run a steam sauna in your home then opt for something larger (over 100L/day) and prioritise features like auto restart and dual compressor technology.

Ease of use

When shopping around, make sure the units are easy to carry up stairs and that all ports and tanks can be removed easily when it's time to empty them. Be aware that some models need to be drained every 12 hours if they're working at maximum capacity, so factor this into your thinking.

Removable tanks

If you need to carry the tank around your home for emptying you'll want it to be small and lightweight. Look out for units with removable lids and handles that make carrying an empty tank up and down stairs a lot easier than carrying a large cylinder-style unit. Units with wheels attached to their base will also help here as they allow the machine itself to move freely, leaving you with just one hand required for moving the water tank around.

Continuous drainage options

Some dehumidifier models offer continuous drainage options (i.e., no need to empty the tank every 12 hours). Depending on its capacity and the rate of water extraction, you may find that this is a real time-saver.

Maintenance

Most dehumidifiers require some regular cleaning to keep them operating at maximum capacity for longer. Taking care of your unit will ensure it lasts as long as possible and removes more moisture in the air in between servicing sessions. Make sure you check which parts need cleaning regularly and factor in how much work this will add to using the machine.

Noise level

All dehumidifiers make noise when in operation, but powerful models can be quite loud so take note of their decibel rating/s if they're not self-evident from the description on offer.

How does a dehumidifier work?

A dehumidifier collects moisture in the air and transfers it into a removable tank or tray that you'll need to empty regularly. This works somewhat similar to an air conditioner. The dehumidifier's efficiency depends on the machine's capacity, but if you live in an area with too much humidity then expect to empty your unit quite often (or use its continuous drainage option). Desiccant dehumidifiers have silica gel which helps in better absorption of moisture. Refrigeration dehumidifiers work well in a hot humid climate. If you choose a centralised model for your home, cooled coils will take any excess moisture out of the air and send it down through your pipework where it can be collected by your plumbing system (if dehumidifying isn't enough for you then remember that whole-house humidifiers are another option worth considering).

What is the difference between a humidifier and a dehumidifier?

A humidifier raises the humidity level of a room or home, adding moisture to dry or stuffy air whereas dehumidifiers work to remove excess water from the atmosphere using a compressor and fans. High humidity can be monitored digitally on some machines, helping you keep an eye on your home's climate and make adjustments accordingly.

What are the disadvantages of a dehumidifier?

Dehumidifiers are effective at removing moisture from the air but they can also lower your home's relative humidity too much if you don't regulate them properly. If this happens, especially in winter when cold air doesn't hold as much extra moisture as warm moist air, then expect problems with condensation and mould on windowsills and walls. If you're using a dehumidifier to combat condensation then you'll want an energy star certified model. They use less energy and won't increase your heating costs or raise the humid environment by adding water back into the atmosphere if the indoor humidity falls below a set point. Look out for models that monitor relative humidity of the room where they're stationed so they know when it's time to add more moisture level to the dry air.

What are the advantages of a dehumidifier?

Energy-star certified dehumidifiers offer a number of advantages over other home climate control systems like air conditioners. For starters, there's no need to regularly change air filters as they don't work with ionisers and require no maintenance from you once they're up and running. You also won't need to use chemical sprays or humidifying gels/tablets as these machines do the job for you without making any mess whatsoever. Humid weather can cause various allergy symptoms of respiratory illness like dry cough, stuffy nose, runny nose. If you face these health problems in your household then dehumidifiers can help tackle this by removing excess dust particles from the dry air. They help to keep common allergy triggers like dust mites, pet hair and pollen at bay (for maximum effect it's recommended that you invest in an HVAC/ air conditioning system for your entire home). Dehumidifiers give out cooled air so they can lower your greenhouse effect and also help you in saving energy costs on summertime cooling costs by reducing the relative humidity level in your home. They're easy to set up and can be used as portable units if you need extra cooling equipment for a specific area. They help the air conditioner work more efficiently.

How do I maintain my dehumidifier?

The frequency with which you'll need to clean and service your machine will depend entirely on the model in question and how often it's used, but most units will need a weekly cleaning session at least. Most dehumidifiers come with indicator lights that display when they're due for service, although some require the user to check them manually. Check your instruction manual (or consult the manufacturer directly) if you're unsure and stick to their recommendations. This should ensure your unit lasts as long as possible.

Keep an eye out for mould build-up around the water tank or tray of any dehumidifier you buy, especially if you live in humid or cold climates. You may have to clean it regularly like an air conditioner filter.

How do you compare dehumidifiers?

Standard dehumidifiers remove moisture from the air by condensing it onto a cold plate, but smarter models will monitor humid environments in the room before kicking into action. Look out for models with hygrometers so you can tell when your home's humidity is getting too high and machines that have an automatic restart function if they ever get knocked off during use or lose power at any point When you visit home improvement stores, compare air dehumidifiers pay attention to noise levels, running costs and energy efficiency. These factors are all crucial if you're looking to invest in your home climate control system. Make sure whatever model you go for is easy to clean and move around your house (some come with casters) while checking that they're not too bulky for your home.

What are the drawbacks of running a dehumidifier?

Consider how much power your unit will use before purchasing it to ensure you pay for its running costs in the long term. Also, make sure that whatever model you buy is suitable for the size of your home. Some smart models may be unable to lower the high humidity levels down to very low temperatures if they're operating in a larger space and several units working at once could increase air humidity levels rather than reduce them due to increased airflow across their fins. If any machine emits an unpleasant musty smell then this is likely caused by stale water from previous sessions or dirty machinery parts, which should fade after having been cleaned with distilled water and dried thoroughly.

For more information on indoor air quality, take a look at the Your Home website