6.6104.1 Outdoor Supply Air Handling Unit Serving Multiple Dwelling Units or Corridors (All Building Types)

Topic: 
Supply
Subtopic: 
Supply Ventilation Systems
Desired Outcome: 
Air handling unit system installed to provide required ventilation
Note: 
The authority having jurisdiction may require that a licensed professional perform certain tasks outlined in this detail.
For supporting material, see Referenced Standards.
TitleSpecification(s)Objective(s)
6.6104.1a
Pre-inspection

Specifications will be field verified as appropriate to site conditions by installer

Ensure appropriate design for installation

6.6104.1b
Air flow

ASHRAE ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, www.ashrae.org 62.2 and local code requirements should be followed for identifying design airflow rates within apartment dwelling units.

All other areas will follow local code requirements and/or ASHRAE ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, www.ashrae.org 62.1 requirements

Air flows will be measured in accordance with ANSI ANSI American National Standards Institute, www.ansi.org / ACCA ACCA Air Conditioning Contractors of America, www.acca.org Standard 5 or ANSI ANSI American National Standards Institute, www.ansi.org / ASHRAE ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, www.ashrae.org Standard 111 and adjusted to meet design requirements

Provide sufficient outdoor air to desired locations

6.6104.1c
Fan specification

Motors 1 horsepower or larger will meet NEMA premium efficiency standards

Fan will be capable of maintaining a minimum operating static pressure of .25 inches of water column

Ensure proper flow rate of outdoor air fans

Ensure energy efficient delivery of outdoor supply air

6.6104.1d
Intake location

Intake will be installed in accordance with all applicable code requirements and/or the most current version of ASHRAE ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, www.ashrae.org 62.2

Ensure occupant health and safety

Prevent entry of contaminants

Ensure unrestricted airflow

6.6104.1e
Intake fitting

Intake fitting will have an integrated collar at least the same diameter as the duct

Fitting will be appropriate for regional weather conditions and installation location on exterior of building

Effectively draw the required volume of air from outside

Preserve integrity of the building envelope Envelope The separation between the interior and exterior environments of a building that includes a combination of air and thermal barrier

Ensure durable installation

6.6104.1f
Weatherproofing

Exterior termination fitting will be flashed or weather sealed

Water will be directed away from penetration

Weatherproofing will be in accordance with manufacturer specifications

Prevent entry of weather into building shell

6.6104.1g
Pest exclusion

Screen material no less than 1/4" and no greater than 1/2" hole size in any direction will be used

Prevent entry of pests into building shell

6.6104.1h
Damper (if applicable)

Damper will close when system is off

Damper will be installed to open in the direction of the desired flow

Ensure unrestricted air flow

Prevent unintended airflow

6.6104.1i
Wiring

Wiring will be installed by a licensed contractor

Wiring will be installed in accordance with original equipment manufacturer (OEM) specifications, and local and national electrical and mechanical codes

Refer to NFPA NFPA National Fire Protection Association, www.nfpa.org 70: National Electrical Code for installation requirements.

Prevent an electrical hazard

6.6104.1j
Access

Fan, service switch Service switch An electrical switch that controls the complete flow of electricity to a mechanical device , filter, and conditioning coils will be accessible for cleaning, maintenance, and repair

Allow for maintenance or replacement

6.6104.1k
Outdoor/fresh air makeup air handling unit mounting

Air handling unit outlet will be oriented toward the final termination location

Air handling unit will be oriented so the equivalent length of the duct run is as short as possible

Air handling unit will be mounted securely in accordance with manufacturer specifications and local code requirements (in terms of seismic restraints)

Air handling unit will be isolated from the building framing unless specifically designed to be directly attached

Ensure short duct runs to achieve optimum air flows

Ensure mounting is installed securely

Ensure air handling unit housing or building framing does not shake, rattle, or hum when operating

Minimize noise

6.6104.1l
Air handling unit/duct riser connection

Duct will be sealed to the top of the curb (for roof-mounted systems)

Ductwork will be attached via a flexible connection, and will be installed in accordance with OEM and duct design minimum sizing requirements

Provide the most efficient air transfer from outdoor air to supply termination

Prevent noise and vibration

6.6104.1m
Duct connections

All ducts, including intake fitting, will be connected and sealed in accordance with supply duct sealing

Deliver outdoor air to desired locations

6.6104.1n
Insulation

All components outside of the thermal envelope Envelope The separation between the interior and exterior environments of a building that includes a combination of air and thermal barrier will be insulated to a minimum of R-8 or equivalent to local codes

All exposed ductwork outside of the building will be insulated to a minimum R-12, protected from weather exposure, and sealed at all penetrations into building shell

Preserve integrity of the duct system

Prevent heat and energy loss

Prevent condensation in ductwork

6.6104.1o
Register boot to interior surface seal

Register boot will be sealed to interior surfaces with sealants compatible to their intended surfaces

Sealants will be continuous and meet fire barrier specifications

Prevent air leakage around boot

Ensure a permanent seal to the building air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary

Prevent a fire hazard

6.6104.1p
Preventing air leakage caused by air pressure differences between spaces

Walls, ceilings, and floors will be sealed to separate any occupied space from any unconditioned spaces and adjacent dwelling units

Refer to ASHRAE ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, www.ashrae.org 62.2 Addendum J

If system design calls for supply air to enter dwelling units from pressurized corridor to under the door, then door will not be weatherstripped

Ensure occupant health and safety

Prevent unintentional air leakage into the building and dwelling units from other spaces (e.g., adjacent dwelling units, garages, unconditioned crawl spaces, unconditioned attics)

6.6104.1q
Balance and flow

Air flows will be measured and adjusted in accordance with ANSI ANSI American National Standards Institute, www.ansi.org / ACCA ACCA Air Conditioning Contractors of America, www.acca.org Standard 5 or ANSI ANSI American National Standards Institute, www.ansi.org / ASHRAE ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, www.ashrae.org Standard 111 and documented to meet design requirements

Achieve the desired air flows to and from the desired locations

6.6104.1r
Fire dampers

Fire dampers must be accessible for inspection and/or testing by the local authorities; if fire dampers are not accessible from a grill or register, an access door in the ductwork is required

Sealing activities will not interfere with the operation of fire dampers, balancing dampers, or backdraft dampers

Type B fire dampers will be used as required by fire code

Ensure access to fire dampers for safe operation

Minimize static pressure

Maximize air flow

6.6104.1s
Occupant/property manager education

Intake fitting will be labeled "ventilation air intake"

Occupant/property manager will be instructed on purpose and value of system, and instructed to keep underside of door unobstructed (in pressurized corridor designs)

Property manager will be instructed on the maintenance and procedures of maintaining system

Ensure unrestricted air flow

Ensure the durability of the ventilation system