Dehumidifier Running Costs UK: Compressor vs Desiccant Compared

Quick answer: A typical 200W compressor dehumidifier costs about 5p an hour — around £12.60 a month at eight hours a day. Desiccant models draw more (300–700W), so a 500W unit costs about 13p an hour, or roughly £32 a month on the same schedule.

All costs on this page are calculated at the October–December 2026 Ofgem price cap for Direct Debit customers: 26.32p per kWh of electricity, with gas comparisons at 7.97p per kWh. Unit rates vary slightly across the 14 GB regions, so treat these as good averages and check the rate on your own bill.

The sum, and why the two types differ

Running cost = power (kW) × hours × 26.32p per kilowatt-hour. A 200W compressor unit running for an hour uses 0.2kWh: 0.2 × 26.32p ≈ 5.3p. Compressor dehumidifiers condense moisture on a cold coil, which is energy-frugal but works best in warmish rooms. Desiccant models soak moisture into an absorbent wheel and then drive it off with a heating element — that element is why they draw two to three times the power, typically 300–700W.

Damp-season running costs compared

Wattages are typical mid-range figures — check your unit’s label, as compressor models span roughly 150–300W and desiccants 300–700W. A humidistat matters more than the headline wattage: a unit that switches itself off at your target humidity can halve the daily energy compared with one left running flat out.

Compressor or desiccant: which suits your damp problem?

Compressor units are the cheaper runners in heated living spaces above about 15°C, where their cold-coil design works efficiently. In a cold garage, conservatory or unheated spare room, their extraction rate collapses — and that’s where desiccants shine, working consistently down to low temperatures. Desiccants also blow out gently warmed air (that heating element again), which in winter is not wasted: the heat lands in your room at the usual 26.32p/kWh, effectively doubling as a small heater while it dries.

Getting the most from every kilowatt-hour

• Close the door of the room being dried — a dehumidifier fighting the whole house never finishes.
• Set the humidistat to 50–60% rather than “continuous” — dryer than that adds cost without comfort benefit.
• Run it hardest during the worst damp weeks rather than all season by default.
• Drying laundry indoors? A compressor unit running alongside an airer for 8 hours (~42p) can undercut a condenser tumble dryer cycle — compare with our tumble dryer running cost guide.
• Persistent damp is usually a building problem, not an air problem — poor ventilation, cold walls or missing insulation. A dehumidifier manages the symptom while you fix the cause.

Extraction ratings: what “10 litres a day” really means

The headline litres-per-day figure on the box is measured in warm, very humid test conditions — often 30°C and 80% humidity — that a UK home never sees. In a typical British living room a “10L/day” compressor unit might actually pull 3–5 litres, and less in a cold room. That’s normal, not a fault, but it matters for costs: an undersized unit runs continuously and still doesn’t hit its target humidity, while a slightly larger one gets the job done and cycles off. When comparing models, use the litres-per-day figure to rank machines rather than as a promise, and look for the wattage alongside it — extraction per watt is the real efficiency measure.

Sizing for cost: bigger can be cheaper

Counter-intuitively, the larger compressor unit is often the cheaper one to run in a genuinely damp house. A 250W machine that reaches 55% humidity in three hours and then cycles on its humidistat can use less electricity per day than a struggling 150W unit running around the clock — and dry air also feels warmer, letting some households trim the heating a touch. Persistent damp that never improves, though, is a signal to stop paying the electricity bill for it and investigate ventilation, guttering, pointing or insulation instead.

Finally, give the machine a fair fight. Dry the washing near it with the door shut, empty the tank before it trips the float switch overnight, and clean the intake filter monthly — a dusty filter throttles airflow and stretches running hours. A dehumidifier working in a closed, filtered, laundry-free room hits its humidity target in a fraction of the time, and every hour it doesn’t run is 5–13p staying in your pocket.

FAQs

How much does it cost to run a dehumidifier 24/7?

A 200W compressor model with a humidistat cycling around half the time uses about 2.4kWh a day — roughly 63p, or £18.95 a month at the current cap. Left on continuous with no humidistat it would be double that, which is rarely necessary.

Are dehumidifiers cheaper than putting the heating on to stop condensation?

Usually, yes — for the specific job of drying air. Warming a whole room by a couple of degrees costs far more than the 40–60p a day a compressor unit typically needs. But condensation on cold surfaces ultimately points to ventilation and insulation gaps, and fixing those beats paying to dry air forever.

Do dehumidifiers heat the room as well?

Slightly, yes — all the electricity they use ends up as heat in the room, plus a little extra released as the moisture condenses. Desiccant units noticeably warm their airflow, which is a genuine winter bonus; see our guide to which appliances quietly use the most electricity for the wider household picture.