Building Code Glossary
Heat Pump: Building Code Definition
How the IRC 2009, IMC 2009 define heat pump, 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
Heat pump is a defined term in the International Residential Code (IRC) 2009, in Definitions. The code's own words are: “An appliance having heating or heating/cooling capability and that uses refrigerants to extract heat from air, liquid or other sources.” The IMC 2009 defines the same term with different wording, so the controlling text depends on which code governs the question in front of you — the comparison below sets the versions side by side. The term is used in 12 chapters of this corpus, most often in Commercial Energy Efficiency (IECC 2009), Heating and Cooling Equipment (IRC 2009), Hvdronic Piping (IRC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted.
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?
Heat Pump — IRC 2009, Definitions:
An appliance having heating or heating/cooling capability and that uses refrigerants to extract heat from air, liquid or other sources.
What must be verified before using this guidance?
Two of the I-Codes in this corpus define Heat Pump, and the wording is not identical — read the version that governs your question.
| Code | Where it is defined | Definition |
|---|---|---|
| IRC 2009 | Definitions | An appliance having heating or heating/cooling capability and that uses refrigerants to extract heat from air, liquid or other sources. |
| IMC 2009 | Definitions | A refrigeration system that extracts heat from one substance and transfers it to another portion of the same substance or to a second substance at a higher temperature for a beneficial purpose. |
Where heat pump is used in the code
The term appears in 12 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Commercial Energy Efficiency | IECC 2009 | 64 |
| Heating and Cooling Equipment | IRC 2009 | 17 |
| Hvdronic Piping | IRC 2009 | 9 |
| Residential Energy Efficiency | IECC 2009 | 7 |
| Hydronic Piping | IMC 2009 | 7 |
| Energy Efficiency | IRC 2009 | 6 |
| Branch Circuit and Feeder Requirements | IRC 2009 | 5 |
| Specific Appliances, Fireplaces and Solid Fuel-burning Equipment | IMC 2009 | 4 |
| Definitions | IMC 2009 | 3 |
| Definitions | IRC 2009 | 3 |
| Scope and Administration | IRC 2009 | 3 |
| Scope and Administration | IMC 2009 | 2 |
The term in use
How the code actually writes about heat pump, quoted from the 2009 text hosted here:
Heat pumps having supplementary electric resistance heat shall have controls that, except during defrost, prevent supplementary heat operation when the heat pump can meet the heating load.
The minimum unobstructed total area of the outside and return air ducts or openings to a heat pump shall be not less than 6 square inches per 1,000 Btu/h (13 208 mm2/kW) output rating or as indicated by the conditions of the listing of the heat pump.
Joints between polyethylene plastic pipe and tubing or fittings for ground source heat pump loop systems shall be heat fusion joints conforming to Section M21 04.2.1.1, electrofusion joints conforming to Section M2104.2.1.2 or stab-type insertion joints conforming to Section M2104.2.1.3.
The terms heat pump is built out of
The definition above leans on 4 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what heat pump covers:
- Refrigeration System — IFC 2009: A combination of interconnected refrigerant-containing parts constituting one closed refrigerant circuit in which a refrigerant is circulated for the purpose of extracting heat.
- Appliance — IRC 2009: Utilization equipment, normally built in standardized sizes or types, that is installed or connected as a unit to perform one or more functions such as clothes washing, air conditioning, food mixing, deep frying, etc.
- 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.
Heat Pump: 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 IRC | Definitions | |
| Read the definition in the adopted IMC | Definitions | |
| Re-check the requirement that uses it | Commercial Energy Efficiency (IECC 2009) | |
| Re-check the requirement that uses it | Heating and Cooling Equipment (IRC 2009) | |
| Re-check the requirement that uses it | Hvdronic Piping (IRC 2009) | |
| Re-check the requirement that uses it | Residential Energy Efficiency (IECC 2009) | |
| Confirm the dependent definition | Refrigeration System | |
| Confirm the dependent definition | Appliance | |
| Confirm the dependent definition | Liquid | |
| 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
- Refrigeration System: Building Code Definition
- Appliance: 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 heat pump?
The International Residential Code (IRC) 2009 defines it in Definitions as: “An appliance having heating or heating/cooling capability and that uses refrigerants to extract heat from air, liquid or other sources.” 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 heat pump?
In this corpus the term is used across 12 chapters, led by Commercial Energy Efficiency in the IECC 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.
Is an AC unit considered a heat pump?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Definitions: “An appliance having heating or heating/cooling capability and that uses refrigerants to extract heat from air, liquid or other sources.” It is defined in IRC 2009, 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.
What is the downside to a heat pump system?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Definitions: “An appliance having heating or heating/cooling capability and that uses refrigerants to extract heat from air, liquid or other sources.” It is defined in IRC 2009, IMC 2009. It is not the same as System, which the IFC 2009 defines separately as “An assembly of equipment consisting of a tank, container or containers, appurtenances, pumps, compressors and connecting piping.” 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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