Ductwork Repair & Replacement

Bad ductwork usually shows up as rooms that never get comfortable, a system that runs and runs, or noise at the vents. If your equipment is working but the house still feels wrong, the ducts are the next thing to check.

• Hot or cold rooms. Upstairs bedrooms in capes and high ranches, rooms at the end of long attic runs, and additions tied into ducts that were never resized.
• Weak airflow at some vents. Crushed or sagging flex duct, joints that have pulled apart in the attic, or dampers left closed.
• Whistling or roaring at returns. A return that is too small for the system, which also starves the blower and can freeze the cooling coil.
• Dusty house, high bills. Leaks on the return side pull attic or crawlspace air into the system; leaks on the supply side dump cooled air into the attic.
• Sweating ducts or water stains. Uninsulated or poorly insulated ducts in a hot attic collect condensation and drip onto ceilings.
• Old, brittle duct. Original flex duct and dried-out tape in attics that reach well over 100 degrees in summer.

What do we look at? We start with the equipment, then follow the ducts. The goal is to find where air is lost or restricted before recommending any changes.

1. Room-by-room check. Which rooms are uncomfortable, and when. We measure supply temperatures and look at each register and return.
2. Attic, basement and crawlspace. We inspect the runs for disconnected joints, crushed flex, missing insulation and poorly sealed boots and plenums.
3. Return air. We check whether the return is large enough for the blower and whether every closed-off room has a path back to it.
4. Options with a price. Sealing and insulating what is there, replacing sections, adding a return, or rerouting runs. You get the scope and price before work starts.
5. The work. Joints sealed with mastic or foil tape, new duct sections hung and supported properly, insulation added, then airflow checked at the registers.

Duct changes are often part of an installation. On a central air replacement in Deer Park, the new equipment was larger than the old, so we replaced the line set, modified the return duct and relocated the condenser. On a Daikin multi-zone install in Huntington, a ducted air handler in the attic serves the second floor through short runs.

Major duct changes can need local approval; K2 does not file town permits, so confirm the requirements with your building department.

What drives the price? The amount of duct involved and how hard it is to reach. Sealing accessible joints is a small job; replacing every run in a tight attic is a large one.

• Access. Low attics, knee walls and crawlspaces take more labor than an open basement.
• Repair or replace. Sealing and insulating existing duct, versus replacing runs or the trunk line.
• Return air changes. Enlarging a return or adding a second one can mean cutting into walls or ceilings.
• Insulation. Adding insulation to attic ducts so they do not lose cooling or sweat.
• Doing it with a new system. Duct changes cost less when they are done alongside an AC or furnace replacement.

Can leaky ducts be fixed, or do they need replacing? If the ducts are the right size and in fair shape, sealing the joints and adding insulation usually solves the problem at a fraction of the cost of new duct. Replace when runs are crushed, brittle or badly undersized, or when a new system needs more airflow than the old ducts can carry.

When you are replacing central air or a furnace, it is the best time to fix the ducts, because the system is open and the new equipment can be matched to them. See AC installation and furnace replacement. Our article on ductwork in older homes covers why older Long Island houses are tricky. Financing is available through Rheem KwikComfort, with credit provided by Synchrony Bank, subject to credit approval. See financing for how it works.

Upstairs rooms in Long Island capes and high ranches sit right under the roof, and their supply ducts usually run through the hottest part of the attic, often the longest runs in the house. By the time cooled air arrives, it has picked up heat, and the return path from those rooms is often weak. Insulating and sealing those runs, adding a return upstairs or adding a separate zone or ductless unit for the second floor are the usual fixes.

Yes. Return-side leaks in an attic or crawlspace pull in dusty, humid air that the system then has to filter and dry. Sealing those leaks keeps that air out, helps the filter do its job and lets the air conditioner remove more moisture from the house. If the system is also short cycling, see our short cycling checklist.

Related services: AC installation, AC repair, furnace replacement, ductless mini-splits and indoor air quality. Long Island guide: AC repair on Long Island.