Manual S® Residential Equipment Selection

Technical Manuals
Manual S®


Manual S 3rd EditionNEWLY RELEASED

Manual S® - Residential Equipment Selection (3rd Edition, Version 1.01) [ANSI/ACCA 3 Manual S - 2023]

View Online ACCA Manual S Normative Section

Purchase Coming Soon! In the meantime, check out the normative section of the 3rd edition.

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ACCA’s Manual S® is a comprehensive guide for selecting and sizing residential heating, cooling, dehumidification, and humidification equipment. It provides size limits to ensure that properly installed equipment can deliver optimal comfort.

The manual is particularly useful because HVAC professionals work in different climates, such as Miami, Phoenix, Seattle, and Denver. It explains how to use heating and cooling loads, the manufacturer’s performance data, and your company’s design conditions to select equipment. The size limits account for regional outdoor conditions, preventing short cycling or safety switch triggers in the units.

The latest revisions to Manual S include:

  • Expanded Definitions: A clearer understanding of standard terms.
  • Support for Code Compliance: Assists in demonstrating compliance with the International Residential Code and the Uniform Mechanical Code. Minimum requirements for documentation are provided.
  • Heat Pump Sizing Tolerances: New expanded size tolerances for variable capacity heat pumps support electrification efforts and allow for heating sizing.
  • Expanded Dehumidification: Provides more guidance on the use of dehumidifiers to improve comfort.

This new edition of Manual S is the culmination of several years of development with cooperation from contractors, users, OEMs, utilities, and other experts focused on equipment selection and sizing.


PREVIEW MANUAL S - 3rd Edition


Manual SManual S® - Residential Equipment Selection (2nd Edition) [ANSI/ACCA 3 Manual S - 2014]

The Second Edition of Manual S shows you how to select and size heating and cooling equipment to meet loads for a particular home based on local climate and home construction specifics. Contractors in Miami, Phoenix, and Seattle - all extremely different climates - would never use the same equipment and expect the same results. Manual S provides sizing requirements for 11 types of cooling and heating equipment, as well as in-depth explanations and examples of how to use the manufacturer's performance data.

Manual S consists of three normative sections, thirteen informative sections, and twenty two appendices across six parts.

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Normative Sections

  • Section N1 - Definitions and General Requirements
    This section defines terminology used throughout Manual S.
  • Section N2 - Equipment Size Limits
    This section outlines required sizing limits for various equipment throughout Manual S.
  • Section N3 - OEM Verification Path
    This section is for when comprehensive data is not available or incomplete. You may use alternative OEM information, provided by the system designer.

Informative Sections

Part 1 - Informative Material Pertaining to Basic Issues and Concepts

  • Section 1 - Equipment Size Issues and Limits
  • Section 2 - Cooling-Only and Heat Pump Equipment Selection
  • Section 3 - Furnace and Water Boiler Selection
  • Section 4 - Humidity Control and Evaporative Cooling Equipment 

Part 2 - Informative Material Pertaining to Central Ducted System Examples and Hydronic Heating Examples

  • Section 5 - Central Duct Air-Air Cooling Examples
  • Section 6 - Central Ducted Air-Air Heat Pump Heating Examples
  • Section 7 - Central Ducted Furnace Examples
  • Section 8 - Dual Fuel Heating Procedures and Examples
  • Section 9 - Central Ducted Water-Air Heat Pump Examples
  • Section 10 - Hydronic Heating Equipment Examples 

Part 3 - Informative Material Pertaining to Ductless Air-Air Equipment

  • Section 11 - Ductless Single-Split Equipment
  • Section 12 - Ductless Multi-Split Systems
  • Section 13 - Single-Package Equipment 

Part 4 - Informative Material Pertaining to Implementation

  • Appendix 1 - Basic Concepts for Air Systems Equipment
  • Appendix 2 - Entering Air Calculations
  • Appendix 3 - Searching OEM Data for Candidate Equipment
  • Appendix 4 - Requirements for Expanded Performance Data 
  • Appendix 5 - Altitude Effects  

Part 5 - Informative Related Information

  • Appendix 6 - Energy and Op-Cost Calculations
  • Appendix 7 - Moisture and Condensation Issues
  • Appendix 8 - Condensation Calculations
  • Appendix 9 - Water-Loop Issues for Water-Air Heat Pumps
  • Appendix 10 - Ductless Multi-Split Piping
  • Appendix 11 - Furnace or Water Boiler Cycling Efficiency
  • Appendix 12 - Matching Evaporators and Condensing Units
  • Appendix 13 - Performance Models for Cooling-Only and Heat Pump Equipment
  • Appendix 14 - Air-Air Heat Pump Supply Air Temperature
  • Appendix 15 - Whole-House Dehumidifier Performance

Part 6 - Informative Ancillary Pages

  • Appendix 16 - Glossary
  • Appendix 17 - Symbols, Acronyms, and Abbreviations
  • Appendix 18 - Summary of Equations
  • Appendix 19 - Supporting Detail for Equipment Sizing Examples
  • Appendix 20 - Rationale for Section N2 Sizing Limits
  • Appendix 21 - Related Resources
  • Appendix 22 - Blank Forms

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Additional Manual S Resources

ACCA Speed-Sheets

ACCA Speed-Sheets are Excel spreadsheets available for purchase that can be used in conjunction with ACCA Technical Manuals, which assist in learning important system design concepts. Speed-Sheets are not a replacement for the full Technical Manual, and are not a replacement for ACCA-approved software.

Learn more about ACCA's Speed-Sheets here.

ACCA Members-Only Resources

Design Essentials - Manual S Residential Equipment Selection
This informative video by Ed Janowiak, Manager of HVACR Design Education, goes over all of the intricate details of residential equipment selection detailed in Manual S.

Predictable Comfort - Manual S
Need 10 minutes or less to catch-up on Manual D? This episode of ACCA’s Predictable Comfort briefly goes over Manual S, including how to calculate based on local climate and home construction specifications.

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