Why You Should Use Your AC’s Dry Mode

In Australia, humidity levels can constantly change, leaving us sweaty and miserable. Our first reaction is usually to turn on our air conditioner’s “cool” setting, assuming it’s the most appropriate way to cool us down.

But it’s not your only option. All units have different settings, and using the right one at the right time can increase its efficiency, save money on your electricity bills, and guarantee a comfortable home environment all year round.

If humidity levels are high and the temperature isn’t too hot, dry mode in AC is an ideal solution in both ducted and reverse cycle air conditioners. Here’s why.

What is dry mode?

The “dry” mode setting on an air conditioning unit is often confused with “cool” mode. When it comes to their effect on temperature, they don’t feel notably different, but they are distinctive in terms of their function. The cool mode is usually represented as a snowflake icon on a unit’s remote, and the dry mode as a water drop. It can be activated with a single touch of a button or in many modern systems through home automation and smart devices.

How does it work?

Just as the temperature changes from season to season, so does the humidity. Your unit’s various air conditioning modes are there for a reason—they cater for a range of weather conditions, whether hot, cold, humid, and dry. Essentially, the purpose of the “dry” function mode is to reduce the excess humidity or moisture in the air, and the cooling effect comes from the removal of that excess moisture.

It works similarly to the cooling mode, but detects temperature differently. So what’s the difference between cool vs. dry mode in AC? In cooling mode, your air conditioner will cool the room and regulate according to the air temperature, returning the air back into the indoor unit. When the system approaches the set temperature, the compressor speed and cooling capacity reduce and it will turn off.

When you switch your air conditioner to dry mode, the unit will record the room temperature and decide what temperature it will cycle off. It then considers and regulates the room/return air temperature and the cooling coil/ heat exchanger temperatures. Fan and compressor speeds will be controlled to maintain the desired temperature differences between the return air and the cooling coil temperature, thereby controlling the humidity of the air being supplied. Essentially, this means the fan inside the unit will still run, but it won’t be blowing out any cool air. It doesn’t replace a dehumidifier as it won’t eliminate all moisture from the room, but keeps it at a comfortable level.

It’s also important to note that the dry mode shouldn’t be used to remove the humidity from the room completely. This is because excess dry air can be just as uncomfortable as a too-humid room! Most air conditioning professionals recommend that units should only run in dry mode for one to two hours at most.

When should I use it?

Humidity, or the amount of moisture in the air feels like an increase in temperature, and when both are present, it can feel irritating and uncomfortable. High levels of humidity can act as an “amplifier” and is one of the reasons that weather forecasts include a “feels like” measure.

Dry mode is ideal when the conditions are humid and “sticky” and temperatures are not too hot, for example, on days when the weather has a tropical feel, and it’s been raining or about to rain. However, this mode won’t perform well on hot summer days — switch to cooling mode at these times. It can also be used in winter, depending on your location’s weather forecast. For example, if it is a cold day and pouring rain outside, you’ll probably be heating your home. The dry mode in this instance will help regulate conditions to a comfortable level.

The recommended range of humidity for indoor environments is between 30 and 50% relative humidity. This refers to the amount of water vapour in the air compared to the maximum amount it could hold at any given temperature.

What are the benefits?

There are many benefits to removing excess moisture and maintaining proper humidity control in your indoor environment, from your family’s health to ensuring a comfortable environment. When used effectively and in the right conditions, dry mode can achieve the following:

A more efficient system

Using your unit’s cool mode consistently in warmer weather isn’t energy efficient — you should only use it during hot and humid seasons — so switch to dry mode when it’s just humid. When using the dry mode, your air conditioner’s compressor runs at a slower pace, so less energy is required. Using it more regularly will reduce your energy costs, and be better for the environment as it will lower your home’s carbon footprint.

A healthier environment

The dehumidification process that occurs in dry mode keeps indoor air at an optimum humidity level, which can improve air quality, and decrease the sweatiness, clamminess and tiredness often associated with high humidity levels. It can also help alleviate common allergy and asthma triggers like mould, mildew and dust mites, which thrive in an excessively humid environment. High humidity can aggravate these symptoms and can even make a usually healthy person ill. Common reactions include a stuffy nose, sneezing, wheezing, difficulty breathing, itchy eyes, skin rashes, reduced resistance to infections, respiratory allergies and a diminished immune system.

A better-protected home

High humidity levels can also cause excessive moisture (and therefore mould and mildew) to develop over time, which often leads to those dreaded “musty odours”. It can appear on furniture, curtains, clothing, towels and bed linen. Mould spores are more likely to grow on walls or in high-humidity areas like showers and bathtubs, water stains may appear on your ceilings or walls, and you may see frequent condensation on the windows. It can also lead to rust or corrosion on tools, home appliances and electronic devices.