How To Repair Ac Duct Insulation

How to Repair Torn or Damaged Ac Ducts

Bert spent 25 years working as a dwelling house-improvement and residential construction contractor in central Florida.

A damaged duct system greatly reduces a heating and air workout organization's free energy efficiency. Ideally, every flake of conditioned air goes directly from the furnace to the living space. In farthermost cases, the free energy lost from torn or damaged ducts far exceeds the price of the repair materials.

This air conditioning unit's duct system uses a galvanized canvass metal plenum with flex duct have offs.

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Types of HVAC Duct

All duct systems serve the aforementioned purpose. Notwithstanding, local building codes oftentimes dictate the type of material used, its installation method and its location.

(Before we get further, remember to e'er wear the appropriate personal protection equipment: such as a dust mask, middle protection, and gloves.)

• Galvanized sheet metal systems: These systems start with a rectangular body line or plenum. The system then runs branch lines, fabricated with either circular sheet metal or smaller rectangular ducts, to the private floor penetrations. S-shaped clips and cleats, oft chosen s-locks and drives, concord the pieces of sheet metallic ducts together; screws hold circular sheet metal ducts together. Installers utilise foil-backed duct tape or canvas metal compatible mastic to seal sheet metal duct. Some applications, such as attic or enclosed systems, demand insulation to prevent condensation while using ac.

• Fiberglass duct board: This blazon of duct uses compressed fiberglass boards with a foil outer layer. A foil-backed duct record, mesh, and duct sealing compound hold each joint together. Manufacturers offer ane-, 1.five- or 2-inch thick ridged fiberglass sheets.

• Flex duct: This easy-to-install and cheap type of duct contain 3 layers: an inner layer that uses a spiral wire rib to hold its shape, a fiberglass center layer that provides thermal protection and an outer layer that acts every bit a vapor barrier. When installing a flex duct, a technician slides the inner liner over a sheet metal collar. Then he seals the inner liner with a code-approved duct tape and locks information technology in place with a big null tie or worm-gear clench, called a duct strap. Installers frequently support flex ducts every four feet. This limits sags and keeps connections from pulling away from the collar.

• Spider systems: A spider system utilizes a centralized plenum that feeds multiple branch lines. Well-nigh branch lines connect to a kicking which delivers air to an interior room. However, when the system needs more than one plenum, a large branch line feeds each additional plenum.

This sail metal duct system runs between flooring trusses.

Past Paul Cutler from Chaska, U.s. (Flickr) [CC BY ii.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

Many homes located in northern climates use galvanized sheet metal ducts. These ducts run through the floor joists. Heat radiating from these ducts helps warm the flooring. Occasionally the sealant loses its grip and allows heated air to escape.

1. Expose the leaking seam: Loosen the hanging straps or brackets on both sides of the repair area. Lower the duct enough to examine the leaking articulation. Normally this type of leak merely needs additional sealant; however, big gaps should be completely exposed and inspected. If a missing or incorrectly installed S-lock caused the large gap, take autonomously the joint and reconnect correctly.
2. Repair the S-lock: When applicative, slice the former mastic from the perimeter of the joint with a utility knife. Remove any screws holding in the S-lock in identify. Straighten the tabs on the ends of both drives and pull them from the joint. Separate the joint. Normally tension prevents complete separation. Slip the old S-lock from the joint. Open the S-lock with a screwdriver and slide it back into place. The flat metal on each duct end should slip into the Due south-lock gap, the gap created by the screwdriver. Install the drives with a hammer.
3. Seal the duct joint: Cover the joint with a 1/eight-inch thick layer of code-approved duct mastic, using a paintbrush to smear the mastic. Manufacturers brand mastic designed specifically for galvanized sheet metal ducts.

Cut fiberglass duct board with a non-serrated knife.

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Fiberglass Duct Board

Heating and ac duct systems using fiberglass duct board rarely need maintenance or repair beyond an occasional interior cleaning. Professional duct-cleaning technicians employ loftier-powered vacuums to evacuate dust buildup from the duct's interior surface. While this type of duct withstands moderate abuse, prolonged exposure to excessive wet contaminates and destroys the fiberglass. Damp sections often dry without any issues, however, due to mold concerns technicians often recommend replacing sections of saturated duct board.

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1. Bleed the duct: The fiberglass layer holds water like a sponge, and an intact foil backing prevents drainage. Place a bucket under the duct and poke a small hole in the duct'south foil outer liner with a screwdriver. Keep the bucket nether the duct until information technology stops dripping.
2. Cut out the damaged section: Strength a non-serrated knife blade through the duct and cut out the wet expanse. Utilise in and out motions. The notches on a serrated knife grab the foil backing'due south reinforcement threads, the triangle-shaped lines visible on the outside of the duct.
3. Create a replacement patch: Either use the one-time department every bit a template or measure the opening with a record measure and transfer the measurements to a new sheet of duct board. Cut the duct lath with a non-serrated knife.
4. Install the patch: Insert the patch into the hole and press on the patch until its foil backing sits flush with the existing duct'southward surface. Apply a slice of foil-backed duct tape to the seam, keeping the middle of the tape centered over the seam. Press the tape with a squeegee. Cover the tape with a piece of mesh. Glaze the mesh with a 1/8-inch thick layer of duct mastic, using a paintbrush as an applicator.

Repairing Other Types of Air Duct Systems

Many duct board systems need the seam effectually the air handler or furnace repaired or sealed. This unremarkably occurs when the installer neglected to wipe all of the manufacturing oil and debris from the air handler'due south surface, or he failed to seal effectually the entire outside perimeter of the plenum.

1. Remove sometime sealant: Cutting away the former sealant, mesh, and record with a knife. Wipe the exposed connexion with a rag, removing whatever droppings or oil.
2. Replace missing or damaged insulation: The duct board insulation must touch the furnace. Otherwise, condensation forms and becomes a breeding ground for mold and mildew.
3. Cover the joint with foil-backed duct tape: The tape should bond the plenum to the furnace.
4. Utilise mesh: Cover the duct tape with mesh. In tight spaces use a paint stick to printing the mesh against the tape.
5. Seal the articulation: Apply a 1/8-inch thick layer of duct mastic to the mesh with a paintbrush. Attach a paint stick to the castor's handle to reach hard to get to areas. Let the mastic harden, using the manufacturer'due south recommended dry fourth dimension, and then turn on the air handler and use a hand to experience for drafts.

In certain situations, such as when the dwelling house'southward pattern places the air-handler or furnace in a pocket-size closet, a tight space prevents the installer from sealing portions of the duct's outer surface. In these cases, the installer must open an access hole and seal the joint from the inside. When doing this, utilize caution to avoid dripping mastic onto the organisation'due south evaporator ringlet.

This ac organisation uses unmarried pieces of flex duct to bridge across the attic

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Flex Duct

Occasionally a home inspection reveals an exposed air-workout duct collar. This happens when pressure forces the outer liner and insulation away from the collar. The exposed collar greatly reduces the arrangement's energy efficiency.

1. Solve the effect causing the exposed collar: Add a hanger strap next to the slipping connexion, relieving any tension. Place additional hanging straps throughout the duct run.
2. Disconnect the loose liner: Cutting the duct strap with wire cutters or pliers. Pull the insulation abroad from the connection. Conform the outer liner, and then it properly covers the insulation.
3. Attach the outer liner: Apply mastic to the outer layer's butt edge. Slide the connexion together and mash the material together until the mastic seals the connection, then lock information technology in place with a duct strap. Cover the outside of the joint with mastic.

Some other mutual type of ac duct damage is torn flex. Tears in the outer liner frequently happen when an installer drags a department of flex duct beyond roof trusses, and the outer liner catches on a blast or truss connector plate. Commonly, the installer notices the damage and repairs it. However, occasionally the harm slips through the inspection and after the warranty catamenia the problem becomes yours.

1. Shut the outer liner's rip: Shut the middle of the rip with a six-inch section of duct tape. Seal each side of the rip with duct tape, starting at the center and working out.
2. Seal the repair: Apply a piece of mesh across the length of the repair. Cover the mesh with duct mastic. The mesh holds the mastic together, which prevents cracks after it drys.

A knife cuts the flex duct's 3 layer and wire cutters snips the wire rib.

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Replacing Flex Duct

In certain situations, such as a crushed duct or animal impairment, it makes more sense to replace a section of flex duct than it does to repair it. The new department uses the original organization'south duct collars and hangers. The cost of materials and the location of the repair make this determination.

1. Remove the damaged flex: If disassembling a flex connectedness, peel away the erstwhile duct seal and cut the duct strap. Pull the insulation away from the connecting, exposing the inner liner. Remove the duct strap and tape holding the liner in place. Carefully slide the damaged duct off the neckband. Skip to step three. When removing a small section of flex duct, technicians slice through the duct with a knife. The bract cuts all iii layers at once and follows the inner liner's wire rib around the perimeter. Remove the pocketknife once it makes a full revolution, snip the wire rib with wire cutters.
2. Install a Splice Connector: Fold the existing duct'southward outer liner over the insulation and slide it betwixt the insulation and inner liner, leaving about iv inches of the liner exposed. Sideslip a splice collar into the end of the duct's inner liner and wrap the connectedness with duct tape. Lock the inner liner against the splice collar with a duct strap. Push the collar into the duct until the collar'southward rib rests flush against the insulation roll.
3. Calculate the length of the replacement department: Mensurate the distance between the existing ducts' collars and add two anxiety. Increase this calculation an additional ane foot for each bend.
4. Cut the new flex to the advisable length: Stretch out the new flex duct to its full length. Roll the outer liner over the insulation and tuck it between the insulation and the inner liner. Measure from the end of the insulation coil to the appropriate place on the duct and cut with a pocketknife. Roll the outer liner over the insulation.
5. Install new flex: Slide the inner liner over the splice collar, leaving almost 1 inch of the collar exposed. Seal the connection with code-approved duct record. Slip a duct strap over the inner liner and tighten it with the advisable tool. Butt the new section'south outer liner and insulation against the existing ducts. Lock information technology in place with a duct strap. Seal the joints with duct record or lawmaking-approved mastic.

This commodity is accurate and truthful to the best of the author's noesis. Content is for informational or entertainment purposes but and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2017 Bert Holopaw

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