How to use an air cooler
Updated: 21 October 2026
You have unpacked a floor unit with a tank, and the booklet is thin on where the water goes. This is how to use an air cooler of the evaporative kind: water in, air through a wet pad, and the tank dried when you stop. It is not a ranking of the six units on the [air cooler comparison](/hub/cooling/air-cooler). Warnings taken from other makers’ manuals are labelled as such. Peter F. did not run these units. A qualifying purchase can earn a commission at no extra cost to you.
You have unpacked a floor unit with a tank, and the booklet is thin on where the water goes. This is how to use an air cooler of the evaporative kind: water in, air through a wet pad, and the tank dried when you stop.
You have unpacked a floor unit with a tank, and the booklet is thin on where the water goes. This is how to use an air cooler of the evaporative kind: water in, air through a wet pad, and the tank dried when you stop. It is not a ranking of the six units on the air cooler comparison. Warnings taken from other makers’ manuals are labelled as such. Peter F. did not run these units. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Tank | Ice packs | Modes | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Midea Midea MCF23XRWUK | 7 L | Included, count n/a | Natural, Vapour, Baby, Sleep, AI | 8.0 | about £140.92 | View offer |
| Best value |  LEENON LEENON ATF-026L | 3 L | 2 | Cooling, Normal, Natural, Sleep | 7.8 | about £119.99 | View offer |
 BLACK+DECKER BLACK+DECKER BXAC65014GB | 6 L | 2 | Normal, Natural, Sleep | 6.3 | about £87.29 | View offer |
On this page
Fill it the way the unit allows
Put the unit on a flat floor, away from curtains, and unplug it before you handle water. That unplug step is in the Sealey SAC45 instructions and in Honeywell’s UK cleaning note. It is not printed on these six listings, so treat it as a class warning, not as a line from a BLACK+DECKER or Midea booklet. On the LEENON, reviewers fill a removable 3 litre tank from a jug and unclip the pump to clean. On the BLACK+DECKER, pulling the 6 litre tank disconnects the pump. On the Air Pro AP-H3, reviews ask where to pour. Use cold tap water. If a clip resists, stop.
Ice, then fan
Add the frozen packs once the tank has water. The BLACK+DECKER, LEENON, APH6, and APH8 include two. The AP-H3 includes four. The Midea includes ice packs and does not print a count. On the APH8, one review says the change lasts about 10 minutes. On the AP-H3, several say ice feels useful for a couple of hours. A LEENON review says not to run cooling with an empty tank. The Sealey SAC45 manual, for a different 45 litre cooler, links an empty Cool setting to pump damage. Do not copy that as a feature of these six. None of them says the pump switches off when the water is gone. Fan-only, if the unit has it, is the dry-tank option.
Give the moisture somewhere to go
Energy Saving Trust says an evaporative cooler cools the air near the machine and that you should keep the room ventilated, and also to keep internal doors closed so the rest of the home’s warm air stays out. A crack of window is the point. No venting on a listing means no exhaust hose. Sit in the stream. A thermometer on the far wall often shows no change, which is a common BLACK+DECKER comment. If the room already feels damp, more running time makes it worse.
Empty and dry
Empty the tank when you stop and let the pad dry. Honeywell’s UK note says drain at least weekly and run fan mode to dry the unit. That is a Honeywell guide, not a claim that these six have a drain plug. If yours has none, jug the water out and run the fan without the cooling pump. The Midea bullet says the filter is washable. Do not scrub a pad the booklet never says you can remove.
Stop here
A damaged mains lead or a unit that trips the socket is not a DIY repair. Unplug it and use the warranty route. The LEENON listing prints one year. The other five print two years. HSE L8 is for dutyholders with cooling towers, not a 3–8 litre bedroom tank. Do not dose a domestic unit from a workplace scheme. If mould or a musty smell continues after you have been emptying and drying the tank, that is a building problem. A split that needs pipes and refrigerant is an installer job. If you are still deciding whether a wet pad belongs in the room, use the air cooler buying guide.
Common questions
Where does the water go if the guide is vague?
Use the opening the reviews actually describe. On the LEENON and the BLACK+DECKER, people pour from a jug because the tank does not lift out without unclipping the pump. On the Air Pro AP-H3, reviewers say the booklet never shows the fill point even though the bullet says the 6 litre tank is removable. Look for a cap, a grille, or a tank hatch before you pull a hose. If a clip resists, stop.
Should cooling mode run with an empty tank?
Do not do that on purpose. A LEENON review warns against running cooling dry, and the Sealey SAC45 manual, for a different cooler, links an empty Cool setting to pump damage. None of these six listings says the pump shuts off when the water is gone. The APH8 page does not answer a question about running without a tank. Fan-only, if the unit has it, is the dry-tank option.
How often should the tank be emptied?
Empty it when you stop for the day, and do not leave water sitting for days. Honeywell’s UK note says at least weekly for its own coolers. These six do not all show a drain plug, so jug or scoop what you poured in, then dry the tank and the pad on fan mode if the unit allows it. Brown water, scale, or a smell is a sign you waited too long, not a normal operating smell.
What if the water smells or looks brown?
Empty it, wash the tank, rinse, and dry it. A LEENON review describes brown water left in the tank. A Midea review describes an algae smell near the minimum level. AP-H3 reviews mention limescale after a few days. That is stale water, not a measured mould result. If the room still smells or shows damp after the tank is clean and dry, stop and treat it as a building issue.
Does a damaged lead or HSE L8 belong in this routine?
A damaged lead is a stop. Unplug the unit and use the warranty path rather than taping a flex. HSE L8 and the evaporative-cooling page are for dutyholders with cooling towers and condensers, not for a 3–8 litre bedroom tank. You do not dose a domestic unit from a workplace scheme. Damp that cleaning does not explain needs a buildings look, not another ice pack.
Related pages
Sources
Public UK sources from the digest, plus the amazon.co.uk listings for these six ASINs, checked on 19 October 2026.
- Energy Saving Trust: tips to keep your home cool (retrieved 19 October 2026)
- Electrical Equipment (Safety) Regulations 2016, regulation 35 (retrieved 19 October 2026)
- HSE: evaporative cooling systems (retrieved 19 October 2026)
- HSE: Legionnaires’ disease, L8 (retrieved 19 October 2026)
- GOV.UK: bans on F-gas in new products and equipment (retrieved 19 October 2026)
- DESNZ Energy Technology List: evaporative air coolers (retrieved 19 October 2026)
- Consumer Rights Act 2015 (retrieved 19 October 2026)
- The Guardian, 13 August 2025: best evaporative air coolers (retrieved 19 October 2026)
- amazon.co.uk listings B0GL7PCKDS, B0H9HZH4R8, B0H9J2FPLP, B0GD6YR1NG, B0GVTYDZ2F, B0DQKCTY1X (retrieved 19 October 2026)