How do I stop condensation on my AC ducts?

Condensation on AC ducts is typically caused by cold ductwork meeting warm, humid air, and can usually be resolved with proper insulation and humidity control.

The most effective solution is duct insulation. If your ducts run through unconditioned spaces like basements, crawl spaces, or attics, they need adequate insulation to prevent the cold surface from reaching the dew point. Look for ducts that appear to be "sweating" - these are prime candidates for insulation upgrades. Existing insulation may have shifted, gotten wet, or deteriorated over time.

Humidity control is equally important. Your home's humidity level should stay between 30-50% during cooling season. If humidity is consistently above 50%, consider running bathroom and kitchen exhaust fans more frequently, using a dehumidifier, or having your AC system evaluated. Sometimes the AC unit is oversized for the space, cooling quickly without adequate dehumidification.

In Ottawa's climate, this problem often occurs during our humid summer months, especially in older homes with ductwork in unfinished basements. Air sealing around ducts is also crucial - any gaps where warm air can contact cold ductwork will create condensation. Check where ducts connect to vents and at joints in the ductwork.

Safety note: Persistent moisture can lead to mold growth, which poses health risks. If you notice musty odors or see visible mold around ducts, this requires immediate professional attention to prevent air quality issues.

If the condensation is severe or widespread, it's worth having a licensed HVAC technician assess your ductwork and insulation. They can identify problem areas and ensure proper vapor barriers are installed. For a comprehensive evaluation of your ductwork and humidity issues, Ottawa HVAC Pro offers free consultations to help resolve condensation problems effectively.