When to buy a desiccant dehumidifier and when to buy a compressor dehumidifier?
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 air temperature is likely to fall below 15°C then you should be buying a desiccant dehumidifier. 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.
Low temperature application – the winner is desiccant
The exceptional to this rule would be a wine cellar. Wine cellars tend to be kept cold and you would not want a desiccant dehumidifier to warm the room back up. For this reason
we use the Meaco 20L in wine cellars to protect the labels and the corks. The advantage of the Meaco 20L is that the humidistat prevents the air from drying out too much and therefore protects the corks.
Wine Cellar application – the winner is compressor
Keeping the house 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 hallway – the winner is desiccant
Warm hallway – the winner is compressor
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 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. Therefore if you want to dry your washing with a dehumidifier then the correct choice is desiccant.
Drying washing – the winner is desiccant
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.
Carrying your dehumidifier – the winner is desiccant
So for a lot of applications the winner is the desiccant dehumidifier and this is reflected in the number that we sell. But there is definitely still a place for compressor dehumidifiers and in a warm home at 18 – 20 something degrees centigrade the compressor dehumidifier will collect more water than the desiccant dehumidifier and it will do so for less money.
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.