🗓 Updated September 17, 2026 · EcoBack editorial team
A heated airer is a drying rack with a low-wattage heating element in the bars. It works, it is cheap to run, and in a British October it is one of the most sensible things you can buy. But it is worth being precise about what it does, because a lot of winter condensation starts on one.
A heated airer does not remove water from your home. It moves it, from the clothes into the air of the room, and it does that faster than an unheated rack would. That is the entire trade.
The number that surprises people
Air can only hold so much water vapour, and at British indoor temperatures it is much less than intuition suggests. Here is how much water the air of an ordinary room can absorb before it is completely saturated, starting from a normal 55% humidity:
| Room | At 16 °C | At 18 °C | At 20 °C |
|---|---|---|---|
| 12 m² bedroom (about 30 m³) | 184 g | 207 g | 233 g |
| 18 m² living room (about 45 m³) | 275 g | 310 g | 349 g |
Grams. Not litres. A spun wash load carries considerably more water than that out of the machine — weigh the basket wet, then weigh it again when the washing is dry, and the difference is what you are about to put into the room.
So the arithmetic does not balance, and it cannot: the air in a small closed room physically cannot hold one load's worth of water. The surplus does not vanish. It condenses, on whatever surface in that room is coldest — which is the window, and the outside wall, and the corner behind the wardrobe. That is where the black spotting comes from, and it is why "the airer caused damp" is a thing people say even though the airer is only doing what it says on the box.
Assumes the door and windows are shut. Any ventilation raises the figure, which is rather the point.
What each machine is actually for
| Heated airer | Dehumidifier | |
|---|---|---|
| What it does | Adds gentle heat to the fabric so water leaves it faster | Takes water out of the room's air and puts it in a tank |
| Where the water ends up | In your air | In the tank, which you empty down the sink |
| Speeds up drying | Yes, strongly at the start | Yes, and it keeps working after the air would otherwise have saturated |
| Risk if used alone in a closed room | Condensation on the cold surfaces | None from moisture; it is the thing removing it |
| Leaves the room warmer | Yes, slightly | Yes — nearly all the electricity becomes heat |
They are complements, not alternatives. The airer moves water out of the clothes; the dehumidifier moves it out of the room. Run the airer alone in a closed bedroom and the drying stalls anyway once the air approaches saturation, because wet fabric only gives up water to air that has room for it.
What it costs, at the current cap
At the Ofgem price cap for 1 October to 31 December 2026, the average electricity unit rate for Direct Debit in England, Scotland and Wales is 26.32p per kWh. This is not a Northern Ireland tariff; regional and plan rates vary. Scale the hours to your own run.
Illustrative fixed-draw examples, not product measurements or matched drying tests. Eight hours is an assumed runtime, not a promise that a load will be dry. The dryer row assumes 2.0 kWh for one cycle; use your own cycle measurement or label basis.
| Example appliance | Assumed draw | Per hour | Energy (8 h; dryer: 1 cycle) | Cost (£) |
|---|---|---|---|---|
| Heated airer, low-wattage | 100 W | 2.6p | 0.8 kWh | 0.21 |
| Heated airer, mid | 200 W | 5.3p | 1.6 kWh | 0.42 |
| Heated airer, three-tier | 300 W | 7.9p | 2.4 kWh | 0.63 |
| Compressor dehumidifier alongside it | 300 W | 7.9p | 2.4 kWh | 0.63 |
| Airer plus dehumidifier (both at 300 W) | 600 W | 15.8p | 4.8 kWh | 1.26 |
| Tumble dryer, one cycle | per cycle | — | 2.0 kWh | 0.53 |
In this example, a 300 W airer plus a 300 W dehumidifier, both running for eight hours, use 4.8 kWh (£1.26). That is 2.4 times the energy of the assumed 2.0 kWh (£0.53) dryer cycle at the same unit rate. This is an arithmetic comparison, not evidence that either setup dries the same load to the same final dryness.
Unit rate only, standing charge excluded — that is a daily fixed cost you pay whether the machine runs or not. There is no VAT on electricity from 1 October 2026 to 31 March 2027. Rate from Ofgem, read 2026-10-04. Your tariff may differ; the sum is watts ÷ 1000 × hours × your rate.
Use the figure on your own airer's plate as an estimate, or measure whole-run kWh. Include the electricity used by any dehumidifier or other powered moisture removal. Compare the same laundry mass and final dryness, with the washing spin, room conditions and actual running hours recorded. A low-wattage appliance running longer can use more energy; the table cannot establish a cheapest method for your home. Space, fabric-care needs and whether you already own a dryer also matter.
The three ways to deal with the moisture
- Ventilate briefly and fully. Free. Cold outside air is dry air once it warms up indoors, so opening up properly for a few minutes exchanges the humid air for air that has capacity. The mechanism and the routine are on our condensation page. A window left ajar all day is the one thing that does not work — it chills the surfaces without exchanging much air.
- Run a dehumidifier in the same room. Costs money, keeps the heat, and is the option that works in a flat you cannot air properly. Which type depends on how cold the room is: desiccant or compressor. In a heated room a compressor unit is the efficient choice, and drying laundry is the one job where it is working in exactly the warm humid air it was designed for.
- Put the airer somewhere that can take it. A bathroom with a working extractor, or the largest and warmest room you have with the door shut to the rest of the flat. The worst place is a cold bedroom with the door closed, which is also where most people put it.
If the damp is already there
If you have black spotting on a wall and you are not sure whether the washing is the cause, check what kind of damp it is before you change anything: rising damp, penetrating damp or condensation. Only the third one has anything to do with your laundry, and the other two will not improve no matter where you dry it.
Frequently asked questions
Does a heated airer cause damp?
Not by itself, but it does put every drop of water from the washing into the air of the room, faster than an unheated rack does. If that room is small, cool or closed, the air saturates and the surplus condenses on the coldest surface in it — usually the window and the outside wall. The airer is not the cause; drying indoors without removing the moisture is.
Is a heated airer cheaper than a tumble dryer?
Not necessarily. Lower wattage alone does not mean a lower cost per dry load. Compare total kWh for the same laundry mass and final dryness, including any dehumidifier or other powered moisture removal. For estimates, use watts divided by 1000, times actual running hours, times your unit rate for each machine, then add the costs. Actual draw, cycling and drying time can vary; a plug-in meter can measure the whole run.
Should I use a heated airer and a dehumidifier together?
They can work together: the airer supplies heat and the dehumidifier removes water from the air. Drying time depends on the load, airflow, room conditions and appliance settings; we have not measured a speed advantage. Count both machines' whole-run electricity use and compare with a dryer only for the same laundry mass and final dryness.
Should I open a window while the airer is on?
Brief, full ventilation works and costs nothing, because cold outside air is dry once it warms up indoors. A window left ajar for hours is the worst of both, chilling the surfaces the moisture will land on while barely exchanging any air. If you want the room to stay warm, a dehumidifier does the same job without losing the heat.