🗓 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, electricity on a Direct Debit tariff is 26.32p per kWh. Scale the hours to your own run.
| Machine | Plate | Per hour | 8 hours (one drying session) | 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 |
| Tumble dryer, one cycle | per cycle | — | 2.0 kWh | 0.53 |
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 2026-09-17. Your tariff may differ; the sum is watts ÷ 1000 × hours × your rate.
Use the figure on your own airer's plate rather than the bands above. The honest comparison is not airer against dryer — it is airer plus whatever deals with the moisture against dryer. An airer at 300 W for eight hours plus a 300 W dehumidifier for the same eight hours lands close to a tumble dryer cycle, and takes all day. The reasons to choose it are the ones that are not about money: no vent, no heat damage to the clothes, no dryer to buy.
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?
Usually yes per session, because the wattage is far lower, but it takes several hours rather than one and it leaves you with the moisture to deal with. Work it out from the plate on your own airer: watts divided by 1000, times the hours you run it, times your unit rate.
Should I use a heated airer and a dehumidifier together?
In a closed room that is the combination that works, and it is usually faster than either alone. The airer supplies the heat that moves water out of the fabric and the dehumidifier takes that water out of the air, so the drying does not stall as the room reaches saturation. You are paying for both machines, so compare the total against a tumble dryer cycle.
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.