A dehumidifier removes excess moisture from a room, making it feel less humid and stuffy. Contrary to belief, it doesn’t cool a room temperature like an air conditioner would.

They’re used in damp conditions, such as during home renovations or post-flooding, to try and limit the damage to house foundations. Damp can cause mould, and if left untreated, can even cause woodwork to require replacement. Humid rooms are also very uncomfortable, especially during a heatwave or when cooking.

The ideal relative humidity in your home is generally between 30% and 50%, so you may need to hire a dehumidifier to keep this stable in your home. But how can these appliances do just that?



How dehumidifiers work

A dehumidifier will draw warm, stuffy air into its internal mechanisms via a fan. The moisture is kept inside the dehumidifier, and the air is released back into the environment. This moisture forms excess water which is collected in a reservoir, and you usually have to manually empty it every few hours.

You will usually pre-set an ideal level of humidity on the machine. The humidity in the room will be reduced to this level, and then maintained for the length of time required. The dehumidifier can remain running in the background or turn itself off and on when required.

But there are two different types of dehumidifiers, and both work in slightly different ways despite doing essentially the same job. How they work can determine which type you need to hire.

Refrigerant dehumidifiers

Also known as compressor dehumidifiers, these draw in warm air and pass it over cold coils. Water will condense upon contact with these, dripping into the water reservoir.

They work better in a heated room because the room temperature needs to be warmer than the coils. This is how the condensation occurs. If the room is too cold, the coils could also risk freezing. While they can defrost themselves, you don’t want them to be using additional electricity and power to do this rather than focus on dehumidifying the room.

Desiccant dehumidifiers

These dehumidifiers use an absorbent material to draw in and capture moisture from the air. This material is heated, causing the moisture to drip into the water tank. They can work in any temperature or condition, including in low temperatures, making them a better choice than refrigerant dehumidifiers in winter, or an unheated basement or outbuilding.

The cons are that they can cost more to run as they need to work harder to heat the inner material, which means they aren’t necessarily the most energy-efficient option. They can also give out this heat as a by-product. In warmer months, this may not be ideal, but if used in very cold rooms, this can help you save money on heating costs.


Tips before using a dehumidifier

We’ve talked about the room temperature, but these aren’t the only room conditions to consider when you’re setting up a dehumidifier.

  1. Firstly, clean and vacuum before switching your dehumidifier on. You don’t want dust and other particles being disturbed by the appliance, which is particularly relevant if you have allergies. These particles can also clog up the filter quicker, which would require regular maintenance.
  2. Position the dehumidifier as central as possible. It needs a good airflow around it; by a wall, next to furniture or stuck in a corner isn’t ideal, even though you may want it out of site.
  3. Keep emptying the water tank when needed and empty it after every use. This will keep everything working smoothly and also reduce the likelihood of mould build-up. Continuous drainage options are available if you have a suitable pipe and ground level drainage, but this can make things more complicated.
  4. Keep an eye on the amount of water removed. If this is excessive, it could signal an issue which needs to be addressed. Also, wipe the appliance down with a dry cloth regularly.


Can a dehumidifier stop damp and mould?

Yes, a dehumidifier can reduce damp, mould, condensation, and mugginess in a room. They draw in any excess moisture, making these instances a lot less likely to occur.

Sometimes, especially in severe cases, other steps will need to be taken to control these issues too.

  • Open a window or use an extractor fan when cooking or showering
  • Wipe down wet walls and shower screens when finished showering or bathing
  • Seal gaps and cracks and fill in any hairline cracks in walls
  • Open a window when drying clothes indoors
  • Check for leaking pipes, both indoor and outdoor

If your damp problem is severe, or you have suffered water damage, you will need to hire a professional for an assessment and possible repairs. This could include a damp-proof course or replacing plasterwork.


Can I use a dehumidifier to preserve special objects?

Some people may want to use a dehumidifier to preserve speciality machinery, musical instruments or paper documents and photos. This is possible, but the level of humidity required will need to be carefully worked out. Seek specialist advice to know what this is.



Yes. Speedy Services, the UK's leading tool hire company, have a range of dehumidifiers for hire nationwide. Speedy has more than 200 service centres across the nation, hire counters in selected B&Qs and nationwide 4-hour delivery, rotavator hire has never been easier.

You’ll find all the tools you need right here. Why not start planning your next DIY project and open a Speedy account today online or in-store?

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