Compressor vs Desiccant Dehumidifier: Which Is Better for UK Homes?

How Compressor Dehumidifiers Work

Compressor dehumidifiers use a refrigeration cycle to cool air and condense moisture, much like a fridge in reverse.

A compressor dehumidifier draws air over a cold evaporator coil. The moisture in the air condenses on the coil and drips into a collection tank [S1]. The dried air is then slightly warmed by the condenser coil and released back into the room.

This process works best when the ambient air is warm enough for the coils to cool effectively. Below about 15°C, the coils can frost up, reducing efficiency significantly [S1]. Many modern compressor units include an auto-defrost feature to manage this.

• Typical power consumption: 200-300W
• Most efficient at temperatures above 15°C
• Can extract 20-50 litres of water per day depending on model
• Generally noisier than desiccant models due to the compressor motor

How Desiccant Dehumidifiers Work

Desiccant dehumidifiers use a rotating wheel coated with a moisture-absorbing material to strip water from the air.

A desiccant dehumidifier passes air over a rotating wheel impregnated with a desiccant material such as silica gel [S2]. The desiccant absorbs moisture directly from the air. A separate stream of heated air then regenerates the wheel by driving off the absorbed moisture.

Because this process relies on absorption rather than condensation, desiccant dehumidifiers work effectively at much lower temperatures, even down to 1°C [S2]. However, the regeneration process requires a heater, which increases energy consumption.

• Typical power consumption: 300-700W
• Effective at temperatures from 1°C to 35°C
• Generally quieter operation than compressor models
• Lighter and more compact than many compressor units
• Produces slightly warm, dry air which can be beneficial in winter

Energy Efficiency Comparison

At typical UK room temperatures, compressor dehumidifiers use roughly half the electricity of desiccant models to extract the same amount of water.

The key factor is the temperature of the room. At 20°C and 60% relative humidity, a compressor dehumidifier might extract around 20 litres per day using 250W [S1]. A desiccant unit extracting the same volume might consume 500-600W [S2].

However, at temperatures below 15°C, compressor efficiency drops sharply and the unit may not extract much water at all without defrost cycles [S1]. In these conditions, a desiccant model will continue to work effectively, making it the more practical choice despite higher wattage.

• At 20°C, compressor models are roughly twice as efficient per litre extracted
• Below 15°C, compressor efficiency drops significantly
• Below 10°C, desiccant models are usually the only effective option
• Running costs vary significantly based on room temperature and humidity

Which Is Better for UK Homes?

For the majority of UK homes, a compressor dehumidifier provides the best balance of performance and running cost.

UK living rooms, bedrooms, and kitchens are typically heated to 18-22°C during occupied hours. In these conditions, a compressor dehumidifier operates at its most efficient [S1]. If you are treating condensation in a lived-in room, a compressor model will almost always be the cheaper option to run.

Desiccant dehumidifiers come into their own for spaces that are not regularly heated. Garages, workshops, caravans, boats, and unheated utility rooms often sit below 15°C for much of the year [S3]. In these environments, a desiccant unit is far more practical.

• Heated living spaces (18°C+): choose compressor
• Unheated garages and outbuildings: choose desiccant
• Caravans and boats: choose desiccant
• Laundry drying in winter: either can work, but desiccant adds heat to the room

Noise, Weight and Portability

Desiccant dehumidifiers are generally quieter and lighter, making them more suitable for portable use.

Compressor dehumidifiers produce a noticeable hum from the compressor motor, typically around 40-50 dB [S1]. This is comparable to a quiet conversation or a refrigerator. For most people this is acceptable in a kitchen or utility room, but may be noticeable in a bedroom.

Desiccant models tend to be quieter, often between 35-45 dB [S2]. They are also typically lighter, with many models weighing under 8kg. This makes them easier to move between rooms or take on trips to a caravan or holiday home.

• Compressor noise: typically 40-50 dB
• Desiccant noise: typically 35-45 dB
• Compressor weight: often 10-15kg
• Desiccant weight: often 6-10kg
• Both types have carry handles; desiccant units are easier to transport

Cost Comparison

Compressor dehumidifiers have a lower running cost at room temperature, while desiccant models have a lower upfront cost in some cases.

Running costs depend heavily on electricity prices and room conditions. At the current UK cap rate of around 26.32p per kWh [S4], a 250W compressor running for 8 hours costs roughly 52p. A 500W desiccant running for the same period costs roughly £1.05.

Purchase prices vary by model and features. Entry-level compressor dehumidifiers start from around £150-200, while desiccant models can be found from £100-150 [S3]. Higher-capacity or feature-rich models of either type can cost £300 or more.

• Electricity cost assumption: 26.32p per kWh (Ofgem cap rate)
• Compressor 250W for 8 hours: approximately 52p
• Desiccant 500W for 8 hours: approximately £1.05
• Use our dehumidifier running cost calculator to estimate your specific costs
• Factor in both purchase price and running cost over the expected lifetime

Frequently asked questions

Bottom line

For most UK homes with heated living spaces, a compressor dehumidifier offers the best energy efficiency and lowest running costs. Desiccant models are the better option for cold, unheated spaces like garages, caravans, and outbuildings where temperatures regularly fall below 15°C. Consider your room temperature, noise tolerance, and portability needs when making your choice.