The Air Conditioning Contractors of America Educational Institute (ACCA-EI) Standards Task Team (STT) announces an American National Standards Institute (ANSI) second public review for modifications to proposed “Addendum c” to ANSI/ACCA 3 Manual S –2023, Residential Equipment Selection, as a revised industry standard.

The 30-day ANSI public review period is from Oct. 24, 2025 to Nov. 23, 2025. Proposed Addendum c will supplement ANSI/ACCA 3 Manual S –2023, Addendum a –2024, and Addendum b –2024. The modifications to the proposed Addendum c are solely based on comments received during the first public review draft on June 6, 2025.  

Manual S provides procedures for selecting and sizing residential cooling equipment, heat pumps, electric heating coils, furnaces, boilers, ancillary dehumidification equipment, humidification equipment, and direct evaporative cooling equipment. Manual S is also a requirement specified in the International Residential Code and the Uniform Mechanical Code.

A redline review draft of the modifications is available on the ACCA website. Submit comments using the form by Nov. 23.