A new ‘tweak’ – Setting your air-con to ‘Dry’ mode



Not the 'Dry' mode symbol which is shaped like a drop of water.
Note the ‘Dry’ mode symbol which is shaped like a drop of water.


By Lam Seng Fatt


This post is not about a tweak per se, but it is about operating your air-conditioner in a different mode to have the best of both worlds – save on power bills and reduce the noise level.


It started – as is the norm these days – in a post in social media. Someone had posted on my wife’s Facebook a tip about saving power bills by operating your air-conditioner on ‘Dry’ mode instead of ‘Cool’ mode. The ‘Dry’ mode has the symbol of a drop of water on the remote control while the normal ‘Cool’ mode has a symbol shaped like a snow flake.


Since I have been told many times not to believe everything on social media, I decided to probe further…by googling for more information. I found several air-conditioner websites which explained what the ‘Dry’ mode was about. So it was not a hoax.


From www.aircon-servicing.com.sg


What Is The Dry Function Mode In Aircon?


Air conditioners are very convenient devices especially when the temperatures are ridiculously high. When it is cold you can do something about it – wear as many warm clothes as possible. However, when the temperatures become unbearably high, there is only so much you can do about it. Removal of clothes has its limits. A good air conditioning system comes in really handy as it will keep the cool air running in your home and office to make life all that much easier. But what if you have no idea on how to use it? For instance, very few people know how to use the dry mode function that comes with most air conditioners nowadays.


What exactly is dry mode?


Dry mode is often compared and confused with the cool mode. To some extent they do not feel different. Nonetheless, they are very different in terms of function and the result – even the remote control will tell you. On the remote, the dry mode is shown by a symbol which is a water drop; on the other hand the cool mode symbol is frequently a snow flake. The dry function, as aforementioned, is not a common feature of all air conditioners. It is mostly on some varieties of central air conditioning units and window units. The main point of the dry mode is to reduce the humidity in a room. As you probably know, an increase in humidity translates into an increase in temperature. When it is humid, temperatures even those that are relatively low tend to be a bit too uncomfortable.


So, basically the dry function reduces the temperature in a room by lowering the humidity. This function is most convenient during those times of the year when it is humid for instance during the rainy season. During this season the temperatures might not be hot enough to necessitate the need for cold air. The humidity however, is high and quite irritating. One point worth noting is that the dry mode is not meant to remove all the moisture in the room.


The working of dry mode


When the air conditioner is function in dry mode, the fan and other inner components of the device will be running. However, the unit does not blow out any cold air. The air in the room passes through the aircon and the water vapor condenses on the evaporator. Dry air will then exit the unit and flow back into the room. This working of the dry mode is almost similar to that of a dehumidifier. A standalone dehumidifier can be found at just about home improvement or hardware store. This one is better than the air conditioner working on dry mode in the case that you are working on a large room. The air conditioner will only remove some of the moisture and not all.


Assuming that the thermostat is set to 25 degrees C and that the humidity in the room is about 90%, the air conditioner will reduce humidity till the temperature is 25 degrees C in that room. When the aircon is switched on, the fan will start running to suck in the air and the compressor cuts in to facilitate the condensation of the humidity. Once the room temperature has dropped to 25 degrees C then both the fan and compressor will stop. Humidity rises steadily again and so does the temperature. When the temperature goes to 26 degrees C the unit starts running again – the cycle repeats itself.


Note the snow flake symbol of the 'Cool' mode.
Note the snow flake symbol of the ‘Cool’ mode.


Cool or dry – which is better?


Cool mode works almost similar to the dry mode only that when the temperatures drop to 25 degrees C the compressor stops running and the fan is left on alone. In dry mode, it is all about keeping the relative humidity at a comfortable 60%. This happens in both the cool and dry mode but in dry mode this value is maintained. In cool mode, humidity keeps increasing dramatically as the fan continues running. Benefits of using dry mode include:

• Lowering moisture in the room significantly

• Maintaining comfortable temperatures without really cooling

• Energy efficient


Dry mode does not really cool the room. The cooling effect comes from the removal of excess moisture not that the unit is actually cooling the room. By using the dry function of your air conditioning unit you will be spending less money on energy bills. It is a really effective way of keeping the temperatures comfortable.


After reading this explanation, my wife and I decided to try the ‘Dry’ mode and quickly pressed the ‘Mode’ button on the remote control till the drop-of-water symbol appeared and left it in that mode for the entire night just last night. Bear in mind that it has been very hot this Chinese New Year, but our bedroom was cooled down to a quite low temperature in the ‘Dry’ mode.


Another thing I noticed was that the air conditioner became really quiet. Apparently this is due to the fact that the fan operates at a slower speed in ‘Dry’ mode.


Then it struck me that audiophiles should all operate their air-conditioners in ‘Dry’ mode. I have been to several dealers’ showrooms where the rattle and hum of the air-conditioner spoilt the auditioning sessions. Even in some homes with million-ringgit systems, the listening environment is compromised by the sound of air coming out of the air-conditioner (if the component had been regularly serviced) or a rattle (if the air-conditioner had not been serviced for a long time).


So I decided to confirm the quietness of the ‘Dry’ mode in a scientific manner and I downloaded the Sound Meter app into my HTC (Android) smartphone.


This morning, I closed the windows and door of the bedroom, turned off the fan and switched on the 1.5HP York air-conditioner. I stood directly below the air-conditioner and activated the Sound Meter.


In ‘Cool’ mode, the noise level was 32-33dB when the compressor kicked in and 26-27dB when the compressor stopped. When I switched to ‘Dry’ mode, the noise level immediately dropped to 21-23dB.


So I went downstairs where my hi-fi system is, closed the doors and windows and turned on the air-conditioner in ‘Dry’ mode and played some music. Suffice it to say that it was most enjoyable to listen to music without the annoying sound of the air-conditioner’s hum and with the room temperature at a comfortably cool level. And I was not blasting the music at clubbing levels.





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