Ductwork Leaks and What They Cost You

Your heating and cooling system can only be as good as the ducts that carry air through your home. When ducts leak, conditioned air ends up in the attic, crawl space or inside walls instead of your living space. You pay for that air either way. Here is how to tell if you have a problem and what you can do about it.

How duct leaks cost you

Leaky ductwork costs you in several ways:

• Higher energy bills. Your system runs longer to reach the temperature you set.
• Uneven comfort. Rooms at the end of a leaky run may never get warm or cool enough.
• Extra wear on equipment. Longer run times mean more strain on the furnace, air handler and AC.
• Poorer air quality. Return duct leaks can pull in dust, insulation fibers or humid air from attics and crawl spaces.
• Humidity problems. In hot climates, leaks can bring moist air into the home or cause condensation on ducts.

Signs your ducts may be leaking

Watch for:

1. Rooms that are noticeably hotter or colder than others
2. Energy bills that rise without a clear explanation
3. Dusty rooms, even after cleaning
4. Ducts in the attic or crawl space with visible gaps, crushed sections or loose tape
5. Whistling sounds from duct joints
6. A system that seems to run constantly in peak weather

None of these proves a leak by itself, but several together are a good reason to have the system checked.

Common causes

Duct leaks usually come from age, installation or damage:

• Joints that were never sealed well at installation
• Duct tape that dried out and peeled off over time
• Flexible ducts that were crushed, kinked or torn
• Disconnected sections, often in attics where people store items
• Pest damage in crawl spaces and attics
• Poorly sealed connections at registers and at the air handler

How leaks are found and fixed

An HVAC contractor or energy auditor can test your ducts. A duct leakage test pressurizes the system to measure how much air escapes. A visual inspection and an infrared camera can help pinpoint problem areas.

Fixes depend on what they find:

• Sealing joints with mastic or approved foil tape
• Reconnecting and fastening loose sections
• Replacing damaged flex duct or crushed runs
• Insulating ducts that run through unconditioned spaces
• Aerosol sealing, a method that seals leaks from the inside, in some homes

Simple sealing in accessible areas is usually far less expensive than replacing large sections of ductwork. Ask for a written estimate that explains the scope.

Ask about duct sizing too

Not every comfort problem is a leak. Ducts that are undersized, poorly routed or missing returns can cause similar symptoms. If you are replacing your HVAC equipment, ask the contractor whether the existing ducts are properly sized for the new system. A new, efficient unit connected to leaky or undersized ducts may not deliver the comfort or savings you expect.

What you can do yourself

If you are comfortable in your attic or basement, you can look for obvious problems:

• Check for disconnected or crushed ducts.
• Look for gaps where ducts meet registers.
• Keep stored items off flexible ducts.
• Change your HVAC filter on schedule so the system is not working harder than necessary.

Use mastic or foil tape, not standard cloth duct tape, for any small sealing work. Leave major repairs to a professional, especially where ducts connect to the furnace.

Do home warranties cover ductwork?

Some home warranty plans include ductwork as part of heating and cooling coverage, while others offer it only on higher tiers. Coverage often focuses on repairing leaks or failures in the duct system from normal wear. Common exclusions include insulation, registers and grills, ducts that are inaccessible, and problems from improper installation. Some plans also have a lower cost limit for ductwork than for the HVAC equipment itself. Read the contract to see exactly what applies.

How Warranty Wizards can help

Warranty Wizards helps you compare home warranty plans from third-party providers and explains what each covers, including ductwork, before you buy. You can request a free quote for your home.