Selecting the right dehumidifier is a minefield for many people as brands send out conflicting information trying to persuade consumers to buy into the technology that they prefer.  Our sales are pretty much 50/50 between the two technologies which leaves us in an unique situation to provide unbiased advice.

There are two different types on the domestic market – desiccant and compressor; the confusion comes when someone who has never used a dehumidifier before has to decide which one to buy.  Below is a cut and keep guide to make the right choice.

Compressor dehumidifiers are the established way of doing things having been around for 40+ years.  They work by creating a cold surface and when the warm, damp air from within the room comes into contact with the cold surface condensation forms and the water is removed from the air.

A desiccant dehumidifier has no compressor and does not use a cold surface to extract the excess moisture from the air.  Instead it has a desiccant wheel that absorbs the moisture from the air, in a similar way to a sponge.  The desiccant is regenerated by an internal heater so that the process can be repeated time and time again.

Many customers prefer the desiccant dehumidifiers because they are lighter and quieter in operation because of the lack of a compressor.  There are though other things to take into consideration, the following below should help.

Air temperature below 15°C

Let’s start with the easy applications.  Any application whereby the room air temperature is likely to fall below 15°C then you should be looking at a desiccant dehumidifier (see the two exceptions

The Meaco 20L Low Energy Dehumidifier is a popular compressor dehumidifier.

The Meaco 20L Low Energy Dehumidifier is a popular compressor dehumidifier.

below).  This is because the inside of the compressor dehumidifier needs to be colder than the air within the room and the colder the room is the harder the dehumidifier has to work to create that cold surface.  As the temperature starts to fall down towards 10°C then the chances are that the inside of the dehumidifier will get close to freezing, increasing the changes of ice forming on the dehumidifiers cooling coils.  This is why below around 15°C the compressor dehumidifiers are programmed to spend up to two thirds of their time defrosting themselves rather than dehumidifying.

The desiccant dehumidifiers on the other hand have a consistent performance regardless of the temperature.  The only exception to this are the Meaco 20L Low Energy Dehumidifier and the Meaco 25L Low Energy Dehumidryer which are both exception down to 10°C.

Low temperature application – the winner is desiccant but check out the 20L and 25L Low Energy models above 10°C as well.

Keeping the house warm and dry

Most customers are looking for a dehumidifier to keep their home condensation free, the home will be a lot warmer than the cold applications above, and so which dehumidifier is best?

Both types of dehumidifier will warm the air up slightly, that is not to say that they are heaters just that they warm the air up as it passes through the dehumidifier.  The air coming out of the compressor dehumidifier will be about 2°C warmer while the air coming out of a desiccant dehumidifier will be about 10-12°C warmer, quite a difference between the two.  So if you are putting the dehumidifier into a hallway that is on the chilly side then the desiccant makes sense as it will warm it up, but if the hallway is already nice and toasty then the compressor dehumidifier is the correct option.

Cold room – the winner is desiccant

Warm room – the winner is compressor

Low Energy consumption

Lots is made of this and compressor dehumidifiers are in general cheaper to run but you have to remember that you will be mostly using your dehumidifier in the winter months and the extra energy that a desiccant uses is released into the room as heat.  So you get water and heat for your money.  You have to decide if you want/need this warmth or if you just want the cheapest dehumidifier to run.

Please remember that not all compressor dehumidifiers are the same and this is why we launched the Platinum Range to draw people’s attention to our low energy compressor models that use a lot less energy than normal compressor dehumidifiers.

Low Energy– the winner is compressor (for more detail on energy consumption please read this article)

Drying washing

One of the most common reasons why people get condensation and mould is because they are drying washing indoors.  Washing dries because the air around is drier and it gives up the moisture in

The DD8L Zambezi is an unique desiccant dehumidifier with six world firsts.

The DD8L Zambezi is an unique desiccant dehumidifier with six world firsts.

order to be in equilibrium with its surroundings.  Using a dehumidifier to create that dry atmosphere and blowing the dry air across the wet washing is a great way of drying the laundry quickly and ensuring that the moisture from the clothes goes into the dehumidifier rather than spreading around the house and causing problems.

Drying washing using a dehumidifier works in the same way as drying the washing on a line in the summer – honest!  The washing dries fastest outside on a dry, warm, windy day, the washing inside will dry faster if the warm, dry air from the dehumidifier hits the clothes.  The desiccant dehumidifier tends to have a larger faster air flow than a compressor dehumidifier and as we have seen above the air coming out of the dehumidifier is warmer.  The Meaco 25L Low Energy Dehumidryer has been designed as an alternative to the tumble dryer and has a massive top speed on its air flow to speed up drying, this combined with its DC Invertor makes this the cheapest compressor dehumidifier to dry laundry.  The DD8L Zambezi has a unique low energy drying cycle for laundry which makes it the best desiccant for drying laundry.

Drying washing – the winners are the DD8L Zambezi and the 25L Low Energy Dehumidryer

Moving the dehumidifier around the house

In general terms you should leave the dehumidifier in the one spot and as long as the internal doors are open the moisture in the house will migrate towards the dehumidifier until it is close enough for the dehumidifier fan to pull it in.

There are some cases though when you are likely to want to move the dehumidifier around.  You might have built-in wardrobes in a bedroom that are up against a north facing outside wall and are prone to mould growth.  You might have the dehumidifier upstairs on the landing but need to move it downstairs to dry the washing, or you might like to move it into a conservatory now and again or use it to dry out a poorly ventilated bathroom.

Compressors add about 6Kgs to the weight of a dehumidifier so carrying a desiccant dehumidifier around is a lot easier than carrying a compressor dehumidifier around.

Low Noise level

In low fan speed desiccant dehumidifiers are all just above or below 40db and you will not get a compressor dehumidifier below 40dB with the exception of the Mitsubishi electric range.  in the middle and top fan speeds the desiccant are the same noise level as compressor machines.  The important point is that at least with desiccant you have the option to switch to a quieter mode which you cannot do with a compressor dehumidifier.

Low Noise level – the winner is desiccant (for more detail on which dehumidifier is quietest please read this article)

Carrying your dehumidifier – the winner is desiccant

You can see that it is not as simple as many dehumidifier brands make out when they claim that desiccant is best or that compressors are best, this is because they are normally biased towards one or other of the technologies.  Hopefully the above will help but if you are still not sure then give us a call on 01483 234900 and we will be happy to talk it through with you.

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Author: Chris Michael

Chris Michael has been in the humidity business since 1989 and founded Meaco in 1991. Much of his knowledge comes from the numerous years spent working with museums and art galleries across Europe controlling and measuring relative humidity to protect the works of art. He is a regular guest speaker on relative humidity at the British Library and is always happy to pass on his knowledge in a practical way to his customers. Outside of Meaco Chris is married with four children and is very active in the local community, especially through youth sport. Further thoughts can be found on Google+ and Twitter