Vents got the sweats?Updated 9 months ago
Condensation is a common factor in air conditioning systems. It happens when warm humid air comes in contact with cold surfaces (ie. a metal vent).
Air conditioning systems are designed to cool air and reduce humidity or moisture in the air. While doing this, sometimes it can generate condensation. Most of the time systems generate condensation at start up - when you turn on the A/C for the first time, or you turn on the A/C when there is hot humid air in the house. More often this happens during summer construction - when trades are coming in and out of the house, and keep outside doors and windows open. In these cases, your system starts pumping cold air through the vents nonstop, while humid hot air clashes with the cool A/C air. Within hours condensation can appear around the vents and will continue as long as the conditions remain the same.
Condensation can also happen if air is coming in through your ducts that is significantly warmer or cooler than the air that is in your home. Your vent may just so happen to be one of the places where they meet and cause the condensation.
One thing to verify is whether or not the flex duct is insulated or if there is sufficient insulation where the vent/duct work is located. Leaks in ducts may also pull outside air which can also cause condensation especially in older homes. If the insulation was already put in place and had to be moved around to accommodate for the vent, if it wasn't replaced or otherwise covered afterwards, then this may be a contributing factor to the condensation. The vent would have almost direct exposure to the unconditioned ceiling space which would cause the condensation.
Condensation may also occur frequently in the bathroom because of the humidity caused by hot showers. It is best to run the bathroom fan during showers or baths for up to 30 minutes after you are finished to help circulate air.
You can take technical proactive steps towards avoiding condensation by consulting your HVAC specialist.