When should I use aircon dry mode?

What aircon dry mode does

Dry mode is the dehumidifying setting on your aircon remote. In its guide to aircon modes, Daikin Singapore says dry mode removes humidity from the room while keeping the indoor temperature as much as possible. Put simply, it goes after the sticky, heavy feeling in the air rather than the heat.

To do that, the indoor unit still runs its cooling coil. Damp room air passes over the cold coil, the moisture condenses into water on the fins, and that water runs into the drain tray and out through the drain pipe. What changes is the aim: pulling water out of the air rather than chilling the room. Other brands may handle dry mode in their own way, so check the manual for your model.

Our guide to aircon settings that save electricity covers the other options on your remote.

Dry mode vs cool mode

The two settings sit side by side on the remote but suit different weather. Daikin says dry mode suits days that are humid but not hot and is not meant for cooling a hot room, while cool mode is the mode for lowering the room temperature.

So when you weigh dry mode vs cool mode, look at the temperature first, not the humidity. A west-facing HDB bedroom at four in the afternoon calls for cool mode. The same room on a grey, drizzly morning, when the air feels heavy but the temperature is mild, is a dry mode day.

If you are unsure what kind of system you have, see inverter vs non-inverter aircon.

When dry mode helps in a Singapore home

Dry mode earns its place on days when the air, not the heat, is the problem. A few common cases:

• Rainy spells. When it rains for days and the windows stay shut, walls and fabrics in an HDB flat or condo can start to feel damp to the touch.
• A bedroom with a damp smell. Ground-floor rooms and rooms in landed homes that get little sun can hold moisture in wardrobes and curtains.
• Laundry drying indoors. A rack of wet clothes in a spare room adds moisture to the air on a wet weekend.
• A closed-up flat. After a week away, a sealed unit can smell stale and feel clammy when you open the door.

Run dry mode in one room with the door and windows closed. If you find yourself using it to keep a store room or wardrobe dry while nobody is in there, a separate unit may suit better. Our guide to using a dehumidifier at home covers when that makes sense.

Does dry mode save electricity

Does dry mode save electricity? It depends on the model, the size of the room, how damp the air is and how long you run it, so be wary of any blanket claim that one mode always costs less to run. Ask the maker about your own unit.

Upkeep is something you can control. NEA advises checking the air-conditioner air filter once a month and cleaning or replacing it when necessary, so that it will run efficiently.

A couple of practical habits help too: use dry mode in a closed room, and set the timer on your remote so the unit switches off once the room feels comfortable. To estimate what your own hours of use might cost over a month, enter your unit's details into the aircon running cost calculator.

Dry mode, mould and smells

Mould grows more easily in damp air, so lowering the humidity in a bedroom makes it less likely to take hold on walls, curtains and the backs of wardrobes. Dry mode will not clean mould that is already there, and it cannot fix a smell coming from the aircon itself.

If the room smells musty only once the unit starts blowing, Daikin's FAQs explain that a foul smell is usually room, furniture or cigarette smells absorbed into the unit and blown back out, and advise getting a qualified serviceman to service it. The same page warns that skipping regular servicing reduces cooling performance, can clog the cooling coil and can lead to water leakage.

For what to look at first, read our guide on why your aircon smells musty.

Signs the unit needs a service

Dry mode works only as well as the unit behind it. Book a check if you notice any of these:

• Weak airflow. Little air comes out even with the fan turned up.
• Dripping. Water runs down the wall or drips from the indoor unit.
• Ice on the pipe. Frost or ice builds up on the pipe. Our post on ice on the aircon pipe explains what it can point to.

Servicing quotes depend on how many units you have and what the job involves. You can compare companies and their published prices on the aircon servicing page.

Questions