Which Dehumidifier?

Refrigerant dehumidifier? Desiccant dehumidifier? Peltier Dehumidifier or silica gel? Let us help you decide.

There are 4 types of dehumidifier available in the UK today, refrigerant, desiccant, Peltier and silica gel, we hope that this will help you to choose which will be best for your application. Refrigerant dehumidifier

Refrigerant with compressor dehumidifiers are by far the most popular in the UK, they draw air in through a filter and pass it over cooling coils similar to the coils on a fridge. The coils are cold and water condenses out from the air and drips into a integral container (most units can be fitted with a hose for permanent drain). The air is then reheated up to room temperature and blown back out of the dehumidifier.

All refrigerant type dehumidifiers lose extraction ability as air temperature reduces, they still work well but the extraction rate will decrease, they are the noisiest out of all the dehumidifiers as they operate with a compressor, the noise level is about the as ame a fridge.

On the positive side, refrigerant dehumidifiers are normally the cheapest on the market with a decent extraction rate and they are very robust. Some building dryers can have very large extraction rates.

This type of dehumidifier is very effective in a home application for protection against damp and for drying clothes, there is also a huge market for them as building dryers and for flood restoration although when used in cold temperatures you should buy one with hot gas defrost to ensure they continue to work down to freezing temperatures, all standard types of dehumidifiers will only take the air down to minimum of 40rH.

Desiccant dehumidifier

Desiccant dehumidifiers have no compressor or refrgererant gases, they uses a slowly spinning wheel made from a  moisture absorbing desiccant material which sucks water from the air, the wheel containing the moistire spins past a heater which evaporates the water into a bucket (or the water can be drained with a hose). The air is reheated to about 10°C above room temperature and is then blown back into the room which make this type of dehumidifier ideal for clothes drying.

Desiccant dehumidifiers extract the same amount of water from the air regardless of th eair temperature, this makes them ideal for protecting items in cold areas such as garages, sheds, boats and caravans as they wion’t lose power in cold temperatures, they are very light and very quiet, they make for excellent clothes dryers since they give off heat and most come with a laundry mode feature and automatic moving louvres.

The negative point with desiccants is that they tend to be more expensive than refrigerant dehumidifiers but they are usually very good quality. The extraction rate is usually quite low, probably between 7 and 10 litres a day which means that 1 unit will dehumidify a 1-2 bedroom flat/house. One feature to look out for if you are protecting somewhere where the power could be cut such as on a boat or in a caravan is the ability to reset and start working again after a power cut.

Peltier dehumidifiers

A Peltier dehumidifier usually has a very small extraction rate, usually less than 1 litre of water a day. They use a cold metal surface to condensate water from the air which then collects in a container.  These units will only dehumidify to around 6%rH less than ambient humidity and should not be used below 15°C,  they will not control the moisture levels in much more than a large wardrobe or small toilet area.

Silica gel dehumidifiers

A silica gel based dehumidifier normally comes in a bag, tub or a rechargeable cassette and should not be used to control moisture in a box, cupboard draw or a wardrobe. You can get a rechargeable type which you plug in to the mains each time it is full to release the moisture with heat, there are a lot of disposable types which are commonly used in caravans and boats.

Which type and size dehumidifier do you need?

  • For normal home dehumidification and if working at normal indoor temperatures we would say that you should follow this rough guide for sizing refrigerant dehumidifiers:

7-10 litres – 1-2 bed house

15 litres – 2-3 bed house

20 litres – 4-5 bed house

25 litres 5+ bed house

  • If you need a dehumidifier for flood restoration or for building drying we would recommend the largest refrigerant dehumidifier you can afford and are able to move around.
  • If protecting a potentially cold area such as a shed, garage, boat or caravan with a power supply we would recommend a 7-10 litre desiccant type dehumidifier.
  • If protecting a wardrobe or cupboard we would recommend a Peltier or silica gel type dehumidifier.
  • If your application is drying clothes then you can use a refrigerant dehumidifier but a desiccant would be slightly better as usually have a laundry mode and kick out some heating also.
  • If used in the bedroom we would not recommend a refrigerant dehumidifier due to noise levels.
  • If your application is a swimming pool you will need a swimming pool dehumidifier with hermetically sealed controls.