Project Specifications

A Note Regarding Service Openings
The National Air Duct Cleaners Association (NADCA) recognizes the need for service openings in HVAC system
components, including air ducts, to facilitate inspection and/or cleaning. NADCA has expanded ACR 2006 to define
minimum requirements for the proper construction and installation of service openings. This document should be cited in
Project Specifications for HVAC system cleaning projects to insure proper access and closure of system components.
In nearly all HVAC system cleaning projects, it will be necessary to make new service openings in duct walls in order to
insert cleaning and inspection equipment. The creation of service openings, and their subsequent closure, requires
craftsmanship and professional skills. Where possible, access to duct interiors should be made by dismantling the ducts
or through existing openings such as supply diffusers, return grilles, duct end caps, and existing service openings.
This Standard applies to the majority of HVAC systems, regardless of the type of duct construction. Service openings
created in any type of system component must meet or exceed the requirements defined herein.
There are two general types of service openings: removable duct access doors and permanent closure panels. Duct
access doors are designed so they can be re-opened without dismantling or altering the system. Permanent closure
panels are pieces of HVAC system material that are sealed and/or fastened permanently upon closure of the service
opening. Depending on the methods used to seal permanent closure panels, it may be possible to remove and re-install
them. Permanent closure panels sealed with gasketing may be removed and re-installed; whereas those closure panels
sealed with mastic or caulking should not be removed. If new service openings will be used in the future for inspection or
cleaning, then removable duct access doors may be most appropriate.