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Right – Metal is mechanically fastened at junction
Right – Metal or fiberboard duct is mastic sealed at junction with duct register box
Right – Metal or fiberboard duct is mastic sealed at seams
Right – Neatly cut and sealed penetration
Right – Penetrations have been neatly cut and properly sealed with foam
Right – Transfer grilles, Jump ducts, and wall grilles provide passive returns for air returning from bedrooms to the central HVAC system
Right – Vent and air barrier sealed
Sheet metal saddles support the flex duct to prevent sagging
Right – Spray foam air seals and insulates raised ceiling duct chase
Run-out duct is sealed with mastic
Run-out ducts are installed over partition walls
Seal all joints and seams in the metal ductwork with mastic before installing insulation
Seal all wood framing joints surrounding the chase with sealant and lay a bead of sealant along top edge of chase framing
Seal all wood framing joints surrounding the chase with sealant and lay a bead of sealant on top edge of chase framing
Seal bottom layer of rigid insulation with adhesive, tape and nails
Seal seams in fiber board ducts with out-clinching staples, UL-181A-approved tape, and mastic
Seams are being properly sealed with mastic and mesh tape
Second layer of rigid insulation is adhered with foam
Seperate dwellings with their own seperate exhaust terminations
Several inches of spray foam lines the attic ceiling, sheltering the HVAC ducts from intense summer sun and providing a temperate storage area.
Sheet metal and mastic provide air sealing around a flue pipe.
Some builders create pan joists by attaching a solid sheet good to the bottom of a floor joist to create a return air pathway
Specially designed roof trusses come with a two-foot by two-foot notch cut next to the center post providing space to install an insulated duct chase inside the home’s conditioned space but above the normal ceiling height.
Spray foam air seals gaps around holes and drywall-to-top plate seams.
Spray foam air seals the boot to the ceiling
Spray foam insulation used for raised ceiling duct chase
Spray foam insulation used for raised ceiling duct chase.
Standard 2 in. by 4 in. stud secures duct chase - made of rigid insulation in this example
Straps are spaced too far apart causing the straps to compress the duct under its own weight
The AC unit has a drip pan and automatic shutoff in case the condensate drain gets clogged.
The attic is sealed and insulated along the underside of the roof deck with 5.5 inches of polyurethane spray foam, providing conditioned space for the HVAC system.
The builder installed plywood under the roof rafters and air sealed it with tape then added a dropped ceiling with metal framing to provide a service cavity for ducts and wiring, without poking holes in the air barrier.
The drywall above the dropped ceiling duct chase extends beyond adjoining top plates for a continuous air barrier
The duct sealing spray injection system includes a blower/heater (background) and the sealant injection unit (foreground)
The duct tester and blower door are set up to measure leakage to the outdoors
The ducts are located within the conditioned space of the home in open-web joists between the floors and the ducts are properly supported to prevent sagging.
The grille in the photo on the left brings air into a return air plenum under an air handler platform. As shown in the infrared image on the right, the plenum is not air sealed so hot attic air is being pulled into the air handler closet.
The high-efficiency air-to-air heat pump is set in an overflow pan with an emergency shut off sensor in case the condensate tube were to clog and cause condensate to fill up the pan.
The HVAC ducts are located between floors in conditioned space, protecting them from cold attic conditions.
The HVAC ducts are located inside the home in a dropped ceiling chase in a central hallway, which provides conditioned space for the ducts and short duct runs for more efficient delivery.
The HVAC ducts are properly supported with wide straps spaced close together.
The HVAC system’s rigid metal ducting is installed between the floor joists rather than in an unconditioned attic or crawl space to minimize heat loss in winter and heat gain in summer.
The inner liner of the flex duct is fastened to the collar with a tension tie, the connection is sealed with mastic, then the outer layer is pulled over and sealed with mastic or foil tape (Steven Winter Associates 2013).
The joints in the ducts and air handler are sealed with mastic.
The jump duct should be insulated and sealed at registers
The main trunk line of the ducts runs within an insulated duct chase installed in a notch designed into the roof trusses that runs the length of the home to provide supply air directly to most of the home’s ceiling registers.
The precast insulated concrete walls of the basement provide a conditioned space for the high-efficiency (18 SEER, 9.5 HSPF) air-source heat pump, with its variable-speed fan, five-stage compressor, and MERV 11 filter.
The round metal HVAC ducts are sealed with mastic at all joints and seams.
The sealed, insulated crawlspace is a clean, dry location to house the main floor heating ducts and also provides bonus storage space.
The seams in this HVAC duct are sealed with mastic.
The tape is covered with mastic to ensure an airtight seal between the duct and the fitting
There should be less than 2.5 inches per each five foot of duct length
These ducts are sealed with Underwriter Laboratories-approved metal tape.
This dropped soffit runs the length of the house providing a convenient place to locate one trunk duct with several very short side ducts that supply heat and cooling to most rooms of the house.
This ducted mini-split heat pump was installed in the unvented, conditioned attic and ducted with short duct runs to several nearby rooms.
This Habitat for Humanity builder ordered roof trusses with a 2-foot by 2-foot notch next to the center post then lined the cutout with rigid foam to form an insulated central duct chase to bring the heating and cooling ducts within the conditioned space.
This home’s ultra-efficient ground-source heat pump provides hot water for space heating as well as domestic hot water for the 50-gallon storage tank.
This utility room houses a high-efficiency gas boiler to provide hot water for the radiant floor heating system and faucets. It also has a central air source heat pump and an energy recovery ventilator.
To attach the flex duct to a main trunk duct or any other connection, the flex duct is pulled over the connecting collar at least 2 inches past the raised bead, then the insulation is pulled back
Total Rater-measured duct leakage ≤ 8 CFM25 per 100 sq. ft. of conditioned area
Transfer grill not sealed
Transfer grill sealed with mastic
Transfer grills and jump ducts provide pathways for air to reach the centrally located HVAC return grille, even when bedroom doors are shut.
Trunk to duct connections are only mechanically fastened and not sealed
Trunk to duct connections are properly insulated and have been sealed with mastic
Twisting and compressing flex duct will block air flow
Two pieces of flex duct are spliced together with a metal sleeve, nylon draw bands, mastic, metal tape, and more mastic
Use only Underwriters Laboratory UL-181 approved tape
Ventilation air inlet is too close to exhaust outlet

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