Why Is My Air Conditioner Sweating? What Causes Dripping Water and How to Fix it

Phill Crawley

Smarter Air & Electrical

i 3 Contents

Air Conditioner Sweating

Have you noticed dripping water or water stains surrounding your ducted air conditioner vents? Found yourself wondering why is my aircon dripping water?

Well, you’re not alone, many other Brisbane homeowners have the same problem during the most humid months of the year! It can be an extremely frustrating problem, but it helps to know the facts. We’ll explain what causes air conditioner sweating, why it hasn’t happened before, and the methods of prevention so you can feel at ease and say goodbye to those pesky water stains.

 

What Causes Air Conditioner Sweating?

 

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1. high Humidity Causes Ducted Air Conditioner Grilles to Sweat

 

Air conditioner sweating occurs when humid air in the home makes contact with the cold surface of the ducted air conditioner grille. Sweating is likely to occur when the air temperature is below the dew point temperature.

The dew point temperature is the temperature at which water vapour will begin to form and turn into liquid. Simply put, if the surface of your air conditioner grille is below the dew point of the room, then moisture will begin to form.

In your roof space where it’s much hotter the dew point temperature is also much higher, this means that sweating of the ducts and other air conditioning equipment is more likely to occur.

 

Examples

Let’s go through an example, at our office today we have just closed all the windows & turned the air conditioner ON. Take a look at our indoor observations below after we closed all the windows.

Indoor temperature: 22.1°C
Relative humidity: 98%
Dew point: 21.8°C.

So, if the external surface of the ducted aircon grilles in our office gets colder than 21.8°C, we could expect water vapour to form and turn into a liquid. As our air conditioner is set to 22°C and won’t be running for a long time, the grilles don’t have the chance to sweat.

February is the most humid month in Brisbane and also the month when most homeowners experience air conditioner sweating problems. Let’s say it’s an average February day and take a look at the dew point temperature.

Indoor temperature: 28.5°C
Relative humidity: 70%
Dew point: 22.5°C

Now we understand that if the external surface of the ducted aircon grilles in our home gets colder than 22.5°C, we can expect water vapour to form and turn into a liquid.

A ducted air conditioner typically provides a 10-12°C difference in temperature between the air getting sucked through the return air filter grille and the supply air temperature coming out of the grille in your living room.

In this example, the standard temperature difference would lead us to a supply air temperature of 18.5°C. As this temperature is lower than the dew point, air conditioner sweating may occur once the metal/plastic grille drops below this temperature.

The material of the grilles can also impact the amount of condensation/ dripping water that comes off your air conditioner. Metal grilles are more likely to cause sweating. Plastic grilles is a better alternative as they are less conductive than metal.

is-your-air-conditioner-sweating-ducted-side

Checklist to Avoid Air Conditioner Sweating

If you are using your system correctly sweating should not be a problem, if it is we need to do some investigating!

  • Are all of the windows and doors shut properly (including the rooms you are not using)
  • Do you have a minimum of 2-3 zones ON & OPEN? Typically set up by your air conditioning contractor and referred to as constant zones. Smarter Air & Electrical sets two constant zones for all systems less than 14kW and 3 for larger air conditioners as often recommended by Advantage Air.
  • Is the unit set to a reasonable and achievable desired temperature for the day such as the recommended 24°C? Doing so gives the unit time to cycle/turn OFF for a period allowing the grille temps to warm back up and prevent them from getting too cold.
  • Are the filters clean? Your filters should be cleaned every three months and more regularly during the summer months. Dirty filters mean a colder temperature at the grille and an increased chance of your air conditioner sweating.  Filters inside air conditioners catch dust particles to avoid you breathing it in. If not cleaned regularly, your filter can clog, causing it to collect moisture and eventually grow mould. Having a clean air conditioner filter allows your family to breathe fresh air all year round.
  • Has your ducted air conditioner system been serviced? The indoor coils of your system might be blocked or dirty. Dirty cooling coils means the airflow is restricted, so you’ll end up with a colder temperature at the grille and again increasing the chance of sweating.
  • Is your roof properly ventilated? The cooler your roof space, the lower the dew point in your roof. This results in a lessened chance of air conditioner sweating occurring of the duct and other equipment in the ceiling. To correct this, reach out to our team to arrange the installation of a few whirlybirds, and cool down your roof & to help prevent sweating.

 

2. Why Hasn’t This Sweating Happened Before?

If your air conditioner has been installed for a few years, there are a few reasons you may not have experienced the issue until now.

  • The cooling coils may be blocked, meaning your indoor unit may need a deep clean. We recommend you have this done at least every three to five years. The deep clean will ensure that any dirt or grime is removed from the indoor coil & ensures that your coils get the correct airflow across them. It also prevents your family from breathing in any mould that may be growing on the coils.
  • Your usage habits may have changed, and maybe you are setting the temperature lower than 24°C? On warm days, we recommend that you set your air conditioner temperature to no more than 10 degrees lower than the outdoor temperature. For example, if it’s 32°C outside, your minimum cooling temperature should be at 22°C.
  • May someone be leaving an outside window or door open resulting in your system sucking in warm, humid outdoor air?
  • If you haven’t installed exhaust fans, your system may be drawing hot, humid air from your roof space! You can check this by looking at the fan when it is turned off, is it spinning in the wrong direction? In this case, you should consider installing a DraftStoppa. Smarter Air can also provide and install this product, so get in touch to arrange installation and reduce air conditioner sweating!
  • You may have added ceiling insulation, and while this is a good thing for your home, it means that the hot air is now trapped in the roof where your ducted air conditioner is located. This means your ducted air conditioner system now has to work harder. The best practice here is to get in touch with Smarter Air, who specialises in roof ventilation using Whirlybirds. Make sure you get some vents installed along with your new roof ventilators.

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3. How Do I Prevent My Ducted Air Conditioner Sweating?

 

Quite often, homeowners look at their ducted air conditioner installation when dealing with sweating or condensation issues and while it’s essential to ensure you have a quality installation, the fact is that most of the time, sweating is rather due to improper use or maintenance of the air conditioner.

Using specialised tools your air conditioning professional will be able to help you pinpoint the problem and suggest ways to help prevent or at least minimise sweating/condensation issues.

Before getting an air conditioning professional involved though it is worth running through the below checklist as you may be able to solve the issue yourself quickly & easily.

  • Ensure all outside windows and doors are CLOSED. One window is all it takes for your system to begin sucking in warm, humid outdoor air which will lead to sweating!
  • Ducted air conditioning systems are typically designed to cool up to 70% of your home at any one time. So, if you have too many zones turned ON, your system will work have to overwork and not cycle off to allow the componentry and grilles to return to room temperature.
  • Make sure you have your desired temperature set to a reasonable temperature, we suggest no lower than 24°C in the summer months. If it is particularly hot outside you should consider raising the desired temperature a little more while sticking to a limit of 10°C lower than the outside temperature. For example, if it’s 36°C outside, ensure your thermostat is set no lower than 26°C. This will reduce your energy consumption and also help prevent your air conditioner from sweating.
  • Take a look at your zone control system and make sure you have at least two constant zones set if your system has a cooling capacity less than 14kW and three constant zones for larger capacity systems.
  • Book in for a deep clean with Smarter Air & Electrical by calling 1300 476 421.

If you have any further questions about air conditioner sweating, installation, or repairs, get in touch with our team today.

Jason Warren
Benji and his team of guys were the most polite, professional and knowledgeable service that we have received. They were on time and the work ...
Jason Warren
Benji and his team of guys were the most polite, professional and knowledgeable service that we have received. They were on time and the work preformed was faultless even to the vacuuming and cleaning at the end. I can not recommend Smarter air and Electrical enough including the initial quote we received and Amanda with her organising and communication. All first class
Jason Warren
Jason Warren
Nicola Alison
10 star review to the team at SmarterAir & Electrical have the WOW factor. Brilliant from start to finish. Having a Property Manager...
Nicola Alison
10 star review to the team at SmarterAir & Electrical have the WOW factor. Brilliant from start to finish. Having a Property Manager background and high standards I know quality service and you were fantastic! The Neo Panasonic unit ducted system is so quiet it’s a dream unit. Don’t even know it is on! Sensors in each room and can remotely turn the system off via the MyPlace app. Specialists in what you do and don’t outsource the annual service shows your genuine accountability “Thank you so much” to all involved, Alex, Davis, Amanda & Chris. Today the installation & electrical team, professional and friendly, Tom, Jake, Eden, Levi, Nav and Will were simply brilliant a Very big Thank you for making my day! They even vacuumed my house and cleaned up & used drop sheets when installing they really looked after my property. I will be adding lights and the garage door to the future to the MyPlace app and also will be upgrading my residential smoke alarms with them. I am a client for life and will recommend you to everyone. Nothing is too much trouble. I chose well and grateful for all of the answers to my questions. It takes a lot to WoW me these days, but you did, thank you for all your hard work.
Nicola Alison
Nicola Alison
Temnit Teshager
I had smart air & electrical for air conditioning service install a new unit and I couldn't be happier with the experience. From scheduling the ...
Temnit Teshager
I had smart air & electrical for air conditioning service install a new unit and I couldn't be happier with the experience. From scheduling the appointment to the completion of the job, everything was seamless. The technician arrived promptly, was courteous, and thoroughly explained the work that needed to be done. They also provided helpful tips for maintaining the unit in the future and cleaned the house after finishing the job.The pricing was fair, and the service was top-notch. I highly recommend them for all your air conditioning needs!
Temnit Teshager
Temnit Teshager
steve fernandes
Had my Panasonic ducted unit installed in December. They did not try and upsell me a unit that was too big for my house size ,...
steve fernandes
Had my Panasonic ducted unit installed in December. They did not try and upsell me a unit that was too big for my house size ,Other companies recommended 1 -2 (16kw-18kw)sizes bigger. Recommended a 12.5kw which would be sufficient for my home size or could get away with the larger 14kw(summers only getting hotter). Ended up going with a Panasonic 14kw Delux unit with MyAir. On the day all the materials were delivered 30 mins (6.30am) before the guys turned up. Started at 7 am and left by 2 pm, They check with me the location of each room where the ducts were going as I have fans as well. House was vacuumed and marks on the wall cleaned. The electrician stayed back till about 3 ish to finish up, test each zone and run through the MyAir tablet. Easy to deal with, quick responses with emails and calls and happy to work with me as I built a stand so my unit was of the ground. Also went up in the ceiling to finish off some work and the ducting is all tidy. Highly recommend!
steve fernandes
steve fernandes
Saji Joseph
Smarter Air and Electrical recently replaced our ducted Air Conditioning system. The team is very professional and their service from start to finish was excellent. ...
Saji Joseph
Smarter Air and Electrical recently replaced our ducted Air Conditioning system. The team is very professional and their service from start to finish was excellent. I would like to extend our special thanks to Jack, Benji, Jacob and Kesan who did the installation and the commissioning. Also, sincere appreciation to all the pre planning work carried out by Davis, Chris, Alex and Amanda. Everything went smoothly from start to finish. Thanks again.
Saji Joseph
Saji Joseph
Darren Maloney
The Smarter Air & Electrical team has been amazing to work with from start to finish. The team have made the process seamless and we ...
Darren Maloney
The Smarter Air & Electrical team has been amazing to work with from start to finish. The team have made the process seamless and we could not be hapier with the finished product. The process has been so good that we have a freind currently getting a system from the team I only have great things to say about my experience it was easy to send them your way. A big thank you to the team and I'm sure I will send more business your way.
Darren Maloney
Darren Maloney
Matthew Harriott
The guys at Smarter Air and Electrical are great. From the inspection and quote through to the install and after sales service the company is ...
Matthew Harriott
The guys at Smarter Air and Electrical are great. From the inspection and quote through to the install and after sales service the company is outstanding. The install team are professional and clean up after them selves. Once mine was complete, they even came back and did a neighbours as well. Highly recommended.
Matthew Harriott
Matthew Harriott
Dallas Werder
From the first interaction, quoting and installation- Absolute outstanding service. They were always on time, polite, professional, attentive and explained everything perfectly. We could not ...
Dallas Werder
From the first interaction, quoting and installation- Absolute outstanding service. They were always on time, polite, professional, attentive and explained everything perfectly. We could not be happier with our ducted air con. Use this company if you want ducted.
Dallas Werder
Dallas Werder
Sue Cee
Once again, brilliant customer service from start to end. Professional, courteous, explaining the process as they went along, Jacob and Will were great. I 100% recommend ...
Sue Cee
Once again, brilliant customer service from start to end. Professional, courteous, explaining the process as they went along, Jacob and Will were great. I 100% recommend Smarter Air & Electrical
Sue Cee
Sue Cee
Bhavesh Bhatt
The guys at Smarter Air did very good job at installing ducted system in my already built home. Starting from their Sales team to...
Bhavesh Bhatt
The guys at Smarter Air did very good job at installing ducted system in my already built home. Starting from their Sales team to customer rep to Electrician and installation team all were very professional and helpful. Highly recommended 👍🏼
Bhavesh Bhatt
Bhavesh Bhatt

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