❄️ Condensation / Sweating on Air Conditioning Grilles
Noticed water forming on your air conditioning vents or ductwork? That’s called condensation — and it’s more common than you’d think.
This usually happens when the cold surface of your ducted air conditioning grilles comes into contact with warm, humid air inside your home. If the grille surface is colder than the dew point of the room, moisture will form — just like a cold drink "sweating" on a hot day.
In warm roof spaces, the dew point is even higher, which means your ductwork and AC equipment are more prone to sweating.
✅ Quick Checklist to Avoid Air Con Sweating
Here are a few simple checks you can do to reduce or stop condensation from forming on your AC system:
🪟 Are all external windows and doors shut properly?
Even the rooms you're not using — open windows let in humid air!
🔁 Are at least 2–3 zones ON and OPEN?
More zones open = better airflow = less condensation risk.
💨 Is the fan speed set to Medium or High?
Higher airflow helps push out humid air and keeps the system efficient.
🌡️ Is the temperature set to 24°C?
This is the recommended set point. It allows the system to cycle off and gives grilles a chance to warm up.
🧽 Are your return air filters clean?
Filters should be cleaned every 3 to 6 months. Dirty filters = restricted airflow = colder grilles.
🛠️ Has your system been serviced lately?
Blocked or dirty indoor coils can restrict airflow and cause excess cooling at the vents.
🌬️ Is your roof space properly ventilated?
A well-ventilated roof means a lower dew point — reducing the chances of sweating up top.
🤔 Why Hasn’t This Happened Before?
If your system suddenly starts sweating, ask yourself:
🔓 Is a window or door being left open, letting in warm, humid air?
🌀 Is the indoor coil blocked or dirty, meaning it needs a deep clean?
🧊 Have you started setting the AC below 24°C? (Lower temps = colder vents)
🌡️ Did you recently install ceiling insulation?
That’s great for comfort, but it may also be trapping heat in your roof, affecting your ductwork.
📌 Summary
Condensation is a natural reaction, but it can usually be prevented with a few simple habits and checks. Keep your system maintained, use it wisely, and you’ll avoid those drips and damp patches!