Ventilation Air Inlet Locations

Scope

Whole House Ventilation

 

The scope below is organized into the following four subcategories:

• All ventilation air inlets located ≥ 10 feet of stretched-string distance from known contamination sources such as stack, vent, exhaust hood, or vehicle exhaust. Exception: ventilation air inlets in the wall ≥ 3 feet from dryer exhausts and contamination sources exiting through the roof.

• Ventilation air inlets ≥ 2 feet above grade or roof deck in Climate Zones 1-3 or ≥ 4 feet above grade or roof deck in Climate Zones 4-8 and not obstructed by snow, plantings, condensing units or other material at time of inspection.

• Ventilation air inlets provided with rodent / insect screen with ≤ 0.5 inch mesh.

• Ventilation air comes directly from outdoors and not from adjacent dwelling units, garages, crawlspaces, or attics.

 

All ventilation air inlets located ≥ 10 feet of stretched-string distance from known contamination sources such as stack, vent, exhaust hood, or vehicle exhaust. Exception: ventilation air inlets in the wall ≥ 3 feet from dryer exhausts and contamination sources exiting through the roof.

 

 

1. Verify locations of all contamination source terminations.
2. Install air inlets at least 10 feet away from all contamination source terminations.
3. Install air inlets at least 3 feet away from dryer exhausts and contamination sources exiting through the roof.

 

Notes:

The outlet and inlet of balanced ventilation systems shall meet these spacing requirements unless manufacturer instructions indicate that a smaller distance may be used. However, if this occurs the manufacturer's instructions shall be collected for documentation purposes.

Contamination Sources

It is important to locate contamination sources away from the air inlets. Contaminated air coming into the home could lead to moisture, odor, or health issues.

The HVAC contractor should coordinate with other subcontractors, including, but not limited to, framers, plumbers, and electricians. This coordination at the beginning of construction will allow for proper placement of both air inlets and contamination source terminations.

Possible contamination source terminations:

• Bathroom exhaust fans

• Plumbing vent pipes

• Kitchen exhaust fans

• Dryer exhaust vents

• Furnace exhaust vents

• Water heater exhaust vents

• Fireplace flues

• Whole-house fans

 

Ventilation air inlets ≥ 2 feet above grade or roof deck in Climate Zones 1-3 or ≥ 4 feet above grade or roof deck in Climate Zones 4-8 and not obstructed by snow, plantings, condensing units or other material at time of inspection.

 

 

1. Coordinate the location of all air inlets prior to installation.
2. Install air inlets at least 2 feet above grade or roof deck in Climate Zones 1-3.
3. Install air inlets at least 4 feet above grade or roof deck in Climate Zones 4-8.

Notes:

It is easier to install an air inlet at the gable end of the house than to try to lift it off the roof 2-4 feet.

 

Click here to access an interactive map of the Residential Prescriptive Requirements for the 2009 International Energy Conservation Code (IECC).

 

ENERGY STAR will permit the use of reduced ventilation air inlet heights in North Carolina. The minimum required height in North Carolina for Climate Zone 4 will be reduced from 4 feet to 2 feet and in Climate Zone 5 from 4 feet to 2.5 feet based on historical snowfall data for this state. Note that ENERGY STAR is evaluating the potential to reduce inlet heights in other regions based upon historical snowfall data.

Air Inlet Locations

It is important for the HVAC contractor to locate air inlets where they will not be blocked by external conditions. Blockage could lead to inadequate air flow in the system. Contaminated air coming into the home could lead to moisture, odor, or health issues.

ENERGY STAR recommends that the HVAC contractor coordinate with other subcontractors, including, but not limited to framers, plumbers, and electricians to understand all possible constraints on air inlet locations. Considering where the air inlet duct is connecting both to the exterior and to the system will prevent the use of ducts that are too long or ones with too many kinks and turns.
HVAC contractors should consult the local code and speak with code officials to understand the constraints of air inlet locations.

 

 

 

Ventilation air inlets provided with rodent / insect screen with ≤ 0.5 inch mesh.

 

 

1. Install rodent/insect screen on all air inlets.
2. ENERGY STAR recommends installing the air inlet in an accessible location that allows for cleaning the screen.

Notes:

Without proper maintenance, ventilation air inlet screens often become filled with debris. Therefore, ENERGY STAR recommends, but does not require, that these ventilation air inlets be located so as to facilitate access and regular service by the owner.

 

 

 

Ventilation air comes directly from outdoors and not from adjacent dwelling units, garages, crawlspaces, or attics.

 

1. Install ventilation ducts to terminate at the exterior.
2. Seal all seams, gaps, holes, and connections to exterior of all ventilation ducts, preferably with mastic.
3. Install duct supports at a minimum of every 5 feet to prevent sagging.
4. Install duct supports without compressing the duct insulation.

Notes:

Air Inlet Locations

It is important for the HVAC contractor to locate air inlets where they will not be blocked by external conditions. Blockage could lead to inadequate air flow in the system. Contaminated air coming into the home could lead to moisture, odor, or health issues.

ENERGY STAR recommends that the HVAC contractor coordinate with other subcontractors, including, but not limited to framers, plumbers, and electricians to understand all possible constraints on air inlet locations. Considering where the air inlet duct is connecting both to the exterior and to the system will prevent the use of ducts that are too long or ones with too many kinks and turns.

HVAC contractors should consult the local code and speak with code officials to understand the constraints of air inlet locations.

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Description

 When a home has a balanced ventilation system that uses a heat recovery ventilator (HRV), energy recovery ventilator (ERV), or central-fan-integrated supply ventilation, fresh air is brought into the home through a ventilation air inlet. To ensure good air quality, the inlet should be placed in a location away from possible sources of contamination, and where it has unobstructed access to clean air. 

 

Possible contamination sources include bathroom exhaust fans, plumbing vent pipes, kitchen exhaust fans, dryer exhaust vents, furnace exhaust vents, water heater exhaust vents, fireplace flues, and whole-house fans. The locations for these outlets and inlets should be specified on plans. In addition, the HVAC contractor should coordinate with other subcontractors, including the framers, plumbers, and electricians, at the beginning of construction to determine the proper placement of both air inlets and contamination source terminations.

 

The air inlet should be located high enough above the ground, or roof surface, to prevent accumulated snow from piling up over it, rainwater from splashing into it, and plants from growing into it. It should be located outside, not in an attic, crawlspace, garage, or attached dwelling. The inlet should be covered with a mesh screen to prevent animal and insect entry. Ideally, it should be placed in a location where the home owner can check and clean it regularly.

 

 

Where to Install Ventilation Air Inlets 

1. Verify locations of all contamination source terminations.

 

2. Install fresh air inlets so that they are

 

• at least 10 feet away from all contamination source terminations
• at least 3 feet away from dryer exhausts and contamination sources exiting through the roof
• at least 2 feet above grade or above the roof deck in Climate Zones 1—3 
• at least 4 feet above grade or above the roof deck in Climate Zones 4—8. 

 

* Note: it is easier to install an air inlet at the gable end of the house than to try to lift it off the roof 2—4 feet.

 

3. Install the air inlet duct in a location with the shortest, most direct path possible to the air handler unit, HRV, or ERV. Stretch the duct tight and support it adequately to minimize sagging and kinks. Air seal around the intake duct termination and seal the duct to the HRV/ERV or return side of the air handler with mechanical fasteners and metal tape or mastic. 

 

4. Install a ≤ 0.5-in.-mesh screen on all air inlets to keep out rodents, insects, and debris.

 

On the diagram of a house below, which has central-fan-integrated supply ventilation, the fresh air intake is located more than 4 feet above grade level and away from other contaminant sources such as other flue or exhaust pipe outlets on the house.

 

Figure 1 - Fresh air inlet on side of house

 

 

The metal frame for the fresh air intake duct grille has been installed in the ceiling of a covered porch of this home under construction. 

Figure 2 - Fresh air inlet located in ceiling of covered porch

 

The intake and duct have been installed for the fresh air inlet in the eave of the roof of this home under construction. The grille has not yet been installed.

 

Figure 3 - Fresh air inlet located in eave of roof

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Ensuring Success

 Visually inspect the ventilation inlet to ensure that it is at least 10 feet from any known contamination sources, at least two feet above grade and above the roof deck in IECC Climate Zones 1-3 and at least four feet above grade and above the roof deck in IECC Climate Zones 4 through 8. Make sure the inlet is not obstructed by any objects, that the ventilation air comes from outdoors—not from a garage, attic, crawlspace, or adjacent dwelling, and that the ventilation inlet is covered with a protective screen with ≤ 0.5–inch mesh.

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Climate

ENERGY STAR Version 3, (Rev. 5)

HVAC System Quality Installation Rater Checklist, Ventilation Air Inlets & Ventilation Source. Ventilation air inlets ≥ 2 ft. above grade or roof deck in Climate Zones 1-3 or ≥ 4 ft. above grade or roof deck in Climate Zones 4-8 and not obstructed by snow, plantings, condensing units or other material at time of inspection. The use of reduced ventilation air inlet heights is permitted in North Carolina. The minimum required height in North Carolina for Climate Zone 4 will be reduced from 4 feet to 2 feet and in Climate Zone 5 from 4 feet to 2.5 feet based on historical snowfall data for this state. Note that the potential to reduce inlet heights in other regions based upon historical snowfall data is being evaluated. 

 

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Compliance

ENERGY STAR Version 3, (Rev. 6)

HVAC System Quality Installation Rater Checklist, Ventilation Air Inlets & Ventilation Source. All ventilation air inlets ≥ 10 ft. of stretched-string distance from known contamination sources such as stack, vent, exhaust hood, or vehicle exhaust. Exception:  ventilation air inlets in the ≥ 3 ft. from dryer exhausts and contamination sources existing through the roof. The outlet and inlet of balanced ventilation systems shall meet these spacing requirements unless manufacturer instructions indicate that a smaller distance may be used.  However, if this occurs, the manufacturer’s instructions shall be collected for documentation purposes. Ventilation air inlets ≥ 2 ft. above grade or roof deck in Climate Zones 1-3 or ≥ 4 ft. above grade or roof deck in Climate Zones 4-8 and not obstructed by snow, plantings, condensing units or other material at time of inspection. The use of reduced ventilation air inlet heights is permitted in North Carolina. The minimum required height in North Carolina for Climate Zone 4 will be reduced from 4 feet to 2 feet and in Climate Zone 5 from 4 feet to 2.5 feet based on historical snowfall data for this state. Note that the potential to reduce inlet heights in other regions based upon historical snowfall data is being evaluated. Ventilation air inlets provided with rodent/insect screen with ? 0.5 inch mesh. Without proper maintenance, ventilation air inlet screens often become filled with debris. Therefore, EPA recommends, but does not require, that these ventilation air inlets be located so as to facilitate access and regular service by the owner. Ventilation air comes directly from outdoors, not from adjacent dwelling units, garages, crawlspaces, or attics.

DOE Challenge Home

Exhibit 1: Mandatory Requirements. EPA Indoor airPLUS Verification Checklist.

Air Conditioning Contractors of America

Air Conditioning Contractors of America. 1995. Manual T Air Distribution Basics for Residential and Small Commercial Buildings.  Manual T provides details on selecting, sizing, and locating supply air diffusers, grilles and registers, and return grilles.

 

American Society of Heating, Air-Conditioning and Refrigeration Engineers (ASHRAE)

ASHRAE Standard 62.2-2010 Ventilation for Acceptable Indoor Air Quality in Low-Rise Residential Buildings for purchase by following link above. The standard provides minimum requirements for mechanical and natural ventilation systems and the building envelope intended to provide acceptable indoor air quality in low-rise residential buildings.

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