Advanced options
Rated wattage is a ceiling: on humidistat control the compressor cycles, so real use is often 50-70% of this (set the duty cycle in advanced options to allow for it). Compressor models suit normal rooms; desiccants draw more but work in cold garages and conservatories and add gentle heat. A dehumidifier by the airer dries laundry for a fraction of a tumble dryer cycle.
What The Dehumidifier Cost Calculator Works Out
- Per day: rated wattage x hours on, divided by 1,000 to get kilowatt-hours, multiplied by the electricity unit rate. A 160W compressor unit running eight hours uses 1.28 kWh, about 34p a day at the current Ofgem price cap unit rate.
- Per month: the daily cost multiplied by the days you run it. A damp-season month on a 10-12 litre unit typically costs GBP 8 to GBP 12, against the mould treatments, ruined coats and redecoration that chronic damp invoices.
- Dehumidifier type: compressor machines (160W to 300W) are efficient in ordinary indoor temperatures but falter below about 15C. Desiccant models (330W to 500W) draw more but work in cold garages, boats and conservatories, exhaust slightly warm air and run quieter. Extraction ratings (10L, 20L a day) are laboratory figures at tropical humidity, so real UK extraction is far lower.
- Laundry-drying context: a four-hour session beside a clothes airer in a closed room, compared with a GBP 1.90 tumble dryer cycle. The dehumidifier dries a load for 20p to 40p and is gentler on clothes.
- Custom wattage (advanced): enter the figure from your own unit's rating plate when none of the presets fits.
- Electricity unit rate (advanced): defaults to the current Ofgem price cap unit rate but is editable for fixed deals, Economy 7 night rates (often 12p to 16p) or time-of-use tariffs.
- Humidistat duty cycle (advanced): the share of the time the compressor is actually running. Once the room reaches the target humidity most units cycle at 50% to 70%, so the label wattage overstates real use. Bigger units on low duty beat small units flat out for both noise and pennies.
- Per hour and per year (advanced): the hourly running cost at your rate and duty cycle, and the monthly cost multiplied by the months you use it. Six months covers a typical October-to-March damp season; 12 suits a permanently damp flat or basement.
- Tumble dryer for the same loads (advanced): what drying the same number of weekly loads in a tumble dryer costs over a year, using your own cost per cycle. Vented and condenser dryers cost GBP 1.50 to GBP 2.50 a cycle; heat pump dryers around 60p to 80p.
- Laundry saving per year (advanced): the tumble dryer total minus the cost of the same loads dried by dehumidifier, which also pins the moisture that would otherwise migrate to the coldest bedroom wall. A dehumidifier manages symptoms, though: persistent damp from poor ventilation, leaking gutters or rising damp needs its cause fixed too.