Do Heat Pumps / Air Conditioners Dehumidify?

The simple answer is yes, air conditioners do dehumidify, but its a byproduct of the cooling function rather than a separate function. With Fujitsu air conditioners, there isn’t a standalone ‘dehumidify’ option. The most effective way to reduce humidity is by using dry mode, which lowers moisture while maintaining energy efficiency..

Let’s look in greater detail at how the dehumidifier works on air conditioners, how they differ from standalone dehumidifiers and whether all air conditioners are able to reduce the amount of moisture in the air.

How Does a Dehumidifier Work on Air Conditioners?

New Zealand's humidity might not be as extreme as other places, but it can still cause discomfort at certain times of year. Cities like Auckland and Tauranga often face muggy summer days, while Wellington and Christchurch can experience damp, chilly winters.

Air conditioners are capable of removing humidity as a normal process in the cooling loop. This natural dehumidifier function in AC systems happens when indoor warm air is exposed to the cold evaporator coils, and the water condenses o the surface. The water drains away, and drier air remains to recirculate back into your room. This process is how an air conditioner dehumidifies the indoor air.

While air conditioners do dehumidify, they’re not as effective at doing so as a dedicated dehumidifier, especially in places with regular high humidity. If you live in an area that’s damp or coastal, setting your unit to ‘dry mode’ will be effective. However, it won’t pull as much moisture out of the air as a standalone dehumidifier designed for that purpose.

Here’s how Dry Mode works:

• The heat pump’s fan and compressor run at a slower, on-and-off cycle.

• Instead of full cooling, the system gently moves warm, humid air across the cold coil.

• As the air cools slightly, moisture condenses on the coil and drains away.

• This lowers the humidity in the room without dropping the temperature too much.

• The result is an efficient way to stay comfortable in damp conditions.

Dehumidifier vs AC

Both units can cut down moisture, but in different ways. Air conditioners remove humidity only as a by-product of cooling the air. An air conditioner will first cool the air, resulting in dehumidification. A dehumidifier, on the other hand, is designed to extract moisture, but it won't lower the room's temperature.

You may find it's worth the money to get a dehumidifier if:

• You live in a very humid or coastal area with perpetual moisture in the air, even with your air conditioner running.

• You notice condensation on windows or musty smells that aren’t resolved by cooling alone.

• You want to reduce mould growth or have allergy symptoms related to high humidity.

• You are drying clothes indoors.

Does a Heat Pump Dehumidify in Winter?

A heat pump won’t dehumidify when it’s running in heating mode. Can you make a heat pump dehumidify in winter? Only if it’s set to cooling or dry mode. Because heating mode doesn’t remove moisture, using a standalone dehumidifier alongside your heat pump can help keep the air drier, reduce condensation on windows and walls.

For the best balance of comfort and efficiency, keep your system at the optimal heat pump temperature in winter and use a dehumidifier to manage dampness.

Purpose of Dehumidification in Heat Pumps / Air Conditioners

Did you know that dehumidifying does more than take away that sticky feel? It also makes your heat pump more energy-efficient. When the air is less humid, your heat pump can cool a room more effectively, which means it doesn’t have to work as hard to maintain the desired temperature. This efficiency can lead to lower power bills, a key consideration for New Zealand families conscious of energy costs.

It’s also worth remembering that air conditioners dehumidify as part of their cooling cycle, helping to create healthier indoor conditions. Lower humidity prevents mould and mildew, which thrive in damp environments and can cause respiratory issues or damage to your home. By keeping indoor air drier, you create a healthier living space for your household.

Lastly, comfort is a big consideration. A 24°C room that is humid can feel much warmer than a room at the same temperature but with low humidity. By reducing moisture, your Fujitsu heat pump helps ensure the temperature feels closer to what the thermostat displays.

To find out more about cost and efficiency control, refer to our guide on Heat Pump Energy Usage.

Key Takeaways with Fujitsu General

Heat pumps / air conditioners do dehumidify, but it’s a by-product of cooling. 

Which should you choose? If cooling is your main goal, using an air conditioner will do the job while also lowering humidity. If moisture is the bigger problem, or you need both solutions, adding a dehumidifier can give you the best of both worlds.