Energy Efficiency Services
Duct Sealing: Stop the Hidden Energy Loss Inside Your Walls and Attic
The U.S. Department of Energy estimates the average home loses 20–30% of conditioned air through duct leaks before it reaches the living space. Duct sealing is one of the highest-ROI home performance improvements available — delivering measurable savings from the first heating or cooling season after service.
Understanding the Service
What Is Duct Sealing
Duct sealing is the process of identifying and permanently closing air leaks in the distribution ductwork of your forced-air HVAC system. Leaks occur at joints, connections, plenums, and wherever duct materials have deteriorated or were never properly sealed during original installation.
Unsealed ducts behave like open holes in your heating and cooling system. In unconditioned spaces like attics and crawlspaces, leaking supply ducts dump expensive conditioned air into empty spaces, while leaking return ducts pull in hot or cold unfiltered air from those same spaces — reducing air quality and forcing the system to work significantly harder to maintain temperature.
Key Benefits
- ?Reduces heating and cooling energy use by 20–30% on average
- ?Prevents conditioned air from escaping into unconditioned attic and crawlspace areas
- ?Reduces infiltration of dust and allergens into the living area from unconditioned spaces
- ?Decreases HVAC runtime and extends equipment service life
- ?May qualify for MassSave rebates and Massachusetts energy efficiency incentive programs
Our Process
How PureFlow Performs Duct Sealing
Duct Blaster Pressure Testing: We perform a duct pressurization test to measure total leakage before any work begins, establishing a precise baseline and setting a target for improvement after sealing.
Leak Location: Using pressure differentials and tracing techniques, we identify the highest-priority leak sites — typically at main trunk connections, flexible duct transitions, boot-to-floor seams, and service access panels.
Mastic & Foil Tape Application: Leaks are sealed using UL 181-rated foil tape and water-based duct mastic — the materials endorsed by ACCA and the Department of Energy for long-term performance. Standard grey cloth duct tape is not used; it loses adhesion within a few years.
Post-Seal Verification: A second pressure test quantifies the reduction in leakage, ensuring all priority locations were addressed.
Know the Signs
Warning Signs You Need This Service
- Chronically high heating and cooling bills
- Rooms that never reach the thermostat setpoint
- Excessive dust near supply registers even after duct cleaning
- Humidity or comfort problems in finished attic or basement spaces
- The HVAC blower runs nearly continuously even in mild weather
Appointment Day
What to Expect From Your PureFlow Visit
Duct sealing appointments start with diagnostic testing and typically take 2–4 hours for a standard home. The process is minimally invasive — most accessible duct sections are located in attics, basement ceilings, and mechanical closets. All sealing materials are safe and odor-free. A written report of before-and-after leakage measurements is provided at appointment completion.
Common Questions
Frequently Asked Questions
Ready to Schedule Duct Sealing
PureFlow's certified technicians serve Greater Boston and surrounding communities. Book online or call for same-day availability.