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Air Sealing the Air Handler Closet

Guide

Guide describing the repair and reconfiguration of the air handler closet and platform when replacing the air handler.

Technology Solutions Case Study: Sealed Air-Return Plenum Retrofit

Case Study

Case study describing the retrofit of a leaky air handler.

Right - All seams in the HVAC equipment and ductwork are sealed with mastic; because the HVAC equipment is in the garage, it is an air-sealed closet.

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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.

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A direct-vent sealed-combustion furnace has dedicated pipes for combustion air and exhaust

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Fiberglass mesh tape is installed around a duct boot in preparation for air-sealing the seams with mastic.

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The gap between the duct boot and the drywall is air sealed by covering the seam with fiberglass mesh tape and mastic.

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A direct-vent sealed-combustion fireplace takes its combustion air directly from outside through a dedicated air inlet and vents combustion products directly outside

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The seam between this duct register and the wood flooring is sealed with caulk to prevent air leakage into the house from the crawlspace below.

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HVAC equipment should never be exposed to the garage; instead, locate them in air-sealed closets, with weatherstripping, spring-loaded hinges, and mastic.

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For homes with heating registers in the ceiling or floor, air seal where the duct boots meet the ceiling drywall or the flooring to prevent heat loss around the register.

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Sealed and Insulated Flex Ducts

Guide

Guide describing how to air seal and insulate flex ducts.

The gaps around this duct boot are sealed with canned spray foam.

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No Ducts or Air Handlers Located in Garage

Guide

Guide describing how to design HVAC systems to be located within the conditioned space of the home, either in a utility closet or in an attic, basement, or crawl space.

Air Conditioning

Guide

Guide describing refrigerant-based compression-cooling air conditioning systems for space cooling.

Right: A well-constructed air handler closet

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Wrong: The door and filter were removed, allowing unfiltered air to enter the air handler leading to premature failure of the system due to dirt accumulation.

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Compact Air Distribution

Guide

Guide describing design and installation of compact duct systems for central heating and cooling systems.

Vented Attic vs Unvented Cathedral Attic Air Flow

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Seal seams in fiber board ducts with out-clinching staples, UL-181A-approved tape, and mastic

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SMACNA HVAC Air Duct Leakage Test Manual (first edition)

Reference

Manual that identifies certain leakage limits for ducts and outlines procedures for testing ducts for conformity with air leakage limits that are set forth in a designer’s project specification.

ECM Air Handler Fans

Guide

Guide describing the use of electronically commutated motors (ECMs) in HVAC central air handler fans to reduce power consumption compared to a single-stage fan motor.

The hole in the drywall was cut overly large for this heating register, allowing air to leak into or out of the wall cavities.

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This air register has noticeable gaps between it and the floor; use canned spray foam to fill in the gaps.

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The dark streaks seen in this infrared camera image of a return vent in a ceiling indicate cooler air is leaking in around the vent.

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With the register grill removed, very large gaps are visible around the edges of this duct boot between the duct boot and the drywall; the gaps can be closed with screw or heavy staples then sealed with caulk, mastic, or metal tape.

Image

Air Sealing the Air Handler Closet

Technology Solutions Case Study: Sealed Air-Return Plenum Retrofit

Right - All seams in the HVAC equipment and ductwork are sealed with mastic; because the HVAC equipment is in the garage, it is an air-sealed closet.

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.

A direct-vent sealed-combustion furnace has dedicated pipes for combustion air and exhaust

Fiberglass mesh tape is installed around a duct boot in preparation for air-sealing the seams with mastic.

The gap between the duct boot and the drywall is air sealed by covering the seam with fiberglass mesh tape and mastic.

A direct-vent sealed-combustion fireplace takes its combustion air directly from outside through a dedicated air inlet and vents combustion products directly outside

The seam between this duct register and the wood flooring is sealed with caulk to prevent air leakage into the house from the crawlspace below.

HVAC equipment should never be exposed to the garage; instead, locate them in air-sealed closets, with weatherstripping, spring-loaded hinges, and mastic.

For homes with heating registers in the ceiling or floor, air seal where the duct boots meet the ceiling drywall or the flooring to prevent heat loss around the register.

Sealed and Insulated Flex Ducts

The gaps around this duct boot are sealed with canned spray foam.

No Ducts or Air Handlers Located in Garage

Air Conditioning

Right: A well-constructed air handler closet

Wrong: The door and filter were removed, allowing unfiltered air to enter the air handler leading to premature failure of the system due to dirt accumulation.

Compact Air Distribution

Vented Attic vs Unvented Cathedral Attic Air Flow

Seal seams in fiber board ducts with out-clinching staples, UL-181A-approved tape, and mastic

SMACNA HVAC Air Duct Leakage Test Manual (first edition)

ECM Air Handler Fans

The hole in the drywall was cut overly large for this heating register, allowing air to leak into or out of the wall cavities.

This air register has noticeable gaps between it and the floor; use canned spray foam to fill in the gaps.

The dark streaks seen in this infrared camera image of a return vent in a ceiling indicate cooler air is leaking in around the vent.

With the register grill removed, very large gaps are visible around the edges of this duct boot between the duct boot and the drywall; the gaps can be closed with screw or heavy staples then sealed with caulk, mastic, or metal tape.

Injected Spray Sealant for Existing HVAC Ducts

Direct Vent Equipment

Concord Cape Prototype

Ducted Returns