Building Code Glossary
Evaporator: Building Code Definition
How the IMC 2009 define evaporator, where the wording differs, and which chapters depend on the term.
On this page
Last updated September 7, 2026 · Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The [ICC code library](https://codes.iccsafe.org/codes) publishes the current model text and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) show which edition a jurisdiction has adopted; those sources control.
Direct answer
Evaporator is a defined term in the International Mechanical Code (IMC) 2009, in Definitions. The code's own words are: “That part of the system in which liquid refrigerant is vaporized to produce refrigeration.” No other I-Code in this corpus defines it, so the IMC 2009 definition is the one to work from. The term is used in 9 chapters of this corpus, most often in Definitions (IMC 2009), Refrigeration (IMC 2009), General Regulations (IMC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted. Record the jurisdiction, the adopted edition, the application date and any local amendment that rewrites the definition before you use it on a live project, because a term redefined by amendment changes every requirement that depends on it.
Content and cited inputs reviewed by Scott Barrington, Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.
What does this term mean?
Evaporator — IMC 2009, Definitions:
That part of the system in which liquid refrigerant is vaporized to produce refrigeration.
What must be verified before using this guidance?
Evaporator is defined once in this corpus, in the Definitions chapter of the International Mechanical Code (IMC) 2009:
That part of the system in which liquid refrigerant is vaporized to produce refrigeration.
Where evaporator is used in the code
The term appears in 9 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Definitions | IMC 2009 | 11 |
| Refrigeration | IMC 2009 | 6 |
| General Regulations | IMC 2009 | 4 |
| General Regulations | IPC 2009 | 4 |
| Heating and Cooling Equipment | IRC 2009 | 3 |
| Commercial Energy Efficiency | IECC 2009 | 2 |
| Means of Egress | IBC 2009 | 1 |
| Means of Egress | IFC 2009 | 1 |
| Definitions | IRC 2009 | 1 |
The term in use
How the code actually writes about evaporator, quoted from the 2009 text hosted here:
Where an evaporator or condenser is located in an air duct system, the volume of the smallest, enclosed occupied space served by the duct system shall be used to determine the maximum allowable quantity of refrigerant in the system.
In addition to the requirements of Section MI411.3, a secondary drain or auxiliary drain pan shall be required for each cooling or evaporator coil where damage to any building components will occur as a result of overflow from the equipment drain pan or stoppage in the condensate drain piping.
Cooling systems shall not use hot gas bypass or other evaporator pressure control systems unless the system is designed with multiple steps of unloading or continuous capacity modulation.
The terms evaporator is built out of
The definition above leans on 3 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what evaporator covers:
- Refrigerant — IRC 2009: A substance used to produce refrigeration by its expansion or evaporation.
- Liquid — IBC 2009: A material that has a melting point that is equal to or less than 68°F (20°C) and a boiling point that is greater than 68°F (20°C) at 14.7 pounds per square inch absolute (psia) (101 kPa).
- System — IFC 2009: An assembly of equipment consisting of a tank, container or containers, appurtenances, pumps, compressors and connecting piping.
Evaporator: what to open, and in what order
Every row is a document this term depends on. The ICC code library and the ICC adoption maps cover the middle rows.
| Check | Where | Confirmed |
|---|---|---|
| Read the definition in the adopted IMC | Definitions | |
| Re-check the requirement that uses it | Definitions (IMC 2009) | |
| Re-check the requirement that uses it | Refrigeration (IMC 2009) | |
| Re-check the requirement that uses it | General Regulations (IMC 2009) | |
| Re-check the requirement that uses it | General Regulations (IPC 2009) | |
| Confirm the dependent definition | Refrigerant | |
| Confirm the dependent definition | Liquid | |
| Confirm the dependent definition | System | |
| Local amendment to any of the above | Jurisdiction's amendment list |
A research aid, not a code determination. The authority having jurisdiction decides which edition and which amendments apply.
Where can you explore related guidance?
- Explore all glossary guidance
- Refrigerant: Building Code Definition
- System: Building Code Definition
- Liquid: Building Code Definition
Sources and method
Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The ICC code library publishes the current model text and the ICC adoption maps show which edition a jurisdiction has adopted; those sources control.
Source links
Frequently asked questions
What is the code definition of evaporator?
The International Mechanical Code (IMC) 2009 defines it in Definitions as: “That part of the system in which liquid refrigerant is vaporized to produce refrigeration.” The 2009 model text is reproduced here; the definition that binds your project is the one in the edition your jurisdiction has adopted, as amended locally.
Which parts of the code depend on evaporator?
In this corpus the term is used across 9 chapters, led by Definitions in the IMC 2009. Those are the sections whose scope moves if the definition is amended locally, so read them together with Chapter 2 rather than on their own.
What does evaporator mean?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IMC 2009 states, in Definitions: “That part of the system in which liquid refrigerant is vaporized to produce refrigeration.” It is defined in IMC 2009. Because it is a defined term, whatever the adopted edition says it means is what every section using it means — so check Chapter 2 of that edition and any local amendment before relying on this wording.
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