# Service Water Heating: Building Code Definition

> How the IECC 2009 define service water heating, where the wording differs, and which chapters depend on the term.

- Canonical: https://harth.build/resources/glossary/service-water-heating/
- Last updated: 2026-09-07
- Data source: 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.

## Key facts

| Fact | Value |
| --- | --- |
| Defined in | IECC 2009 (2009 editions transcribed in this corpus) |
| Primary source | IECC 2009 Definitions (model text, not a jurisdiction's adopted text) |
| Chapters using the term | 5 (counted across the codes hosted here) |
| Wording identical across codes | Single code (compare before citing one code's wording under another) |

## Direct answer

Service water heating is a defined term in the International Energy Conservation Code (IECC) 2009, in Definitions. The code's own words are: “Supply of hot water for purposes other than comfort heating.” No other I-Code in this corpus defines it, so the IECC 2009 definition is the one to work from. The term is used in 5 chapters of this corpus, most often in Commercial Energy Efficiency (IECC 2009), Residential Energy Efficiency (IECC 2009), Administration (IECC 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](https://nz.linkedin.com/in/barrington), Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.*

## What does this term mean?

**Service Water Heating** — IECC 2009, Definitions:

> Supply of hot water for purposes other than comfort heating.

![Labeled code-term definition diagram: Service Water Heating: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/service-water-heating/diagram-1344.webp)

*How the IECC 2009 define service water heating, where the wording differs, and which chapters depend on the term.*

## What must be verified before using this guidance?

**Service Water Heating** is defined once in this corpus, in the [Definitions](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/definitions.md) chapter of the International Energy Conservation Code (IECC) 2009:

> Supply of hot water for purposes other than comfort heating.

## Where service water heating is used in the code

The term appears in 5 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](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/commercial-energy-efficiency.md) | IECC 2009 | 13 |
| [Residential Energy Efficiency](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/residential-energy-efficiency.md) | IECC 2009 | 2 |
| [Administration](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/administration.md) | IECC 2009 | 1 |
| [Definitions](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/definitions.md) | IECC 2009 | 1 |
| [Energy Efficiency](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/energy-efficiency.md) | IRC 2009 | 1 |

### The term in use

How the code actually writes about service water heating, quoted from the 2009 text hosted here:

> The commercial bUilding project shall comply with the requirements in Sections 502 (Building envelope requirements), 503 (Building mechanical systems), 504 (Service water heating) and 505 (Electrical power and lighting systems) in its entirety.

— [IECC 2009 §501.2](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/commercial-energy-efficiency.md)

> The certificate shall list the types and efficiencies of heating, cooling and service water heating equipment.

— [IECC 2009 §401.3](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/residential-energy-efficiency.md)

> mechanical and service water heating system and equipment types, sizes and efficiencies;

— [IECC 2009 §103.2](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/administration.md)


## The terms service water heating is built out of

The definition above leans on 1 other defined term. Each carries its own code definition, and a local amendment to any of them changes what service water heating covers:

- **[Hot Water](https://harth.build/resources/glossary/hot-water.md)** — IRC 2009: Water at a temperature greater than or equal to 110° P (43°C).

## Service Water Heating: what to open, and in what order

Every row is a document this term depends on. The [ICC code library](https://codes.iccsafe.org/codes) and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) cover the middle rows.

| Check | Where | Confirmed |
| --- | --- | --- |
| Read the definition in the adopted IECC | Definitions | |
| Re-check the requirement that uses it | Commercial Energy Efficiency (IECC 2009) | |
| Re-check the requirement that uses it | Residential Energy Efficiency (IECC 2009) | |
| Re-check the requirement that uses it | Administration (IECC 2009) | |
| Re-check the requirement that uses it | Definitions (IECC 2009) | |
| Confirm the dependent definition | Hot Water | |
| 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](https://harth.build/resources/glossary.md)
- [Hot Water: Building Code Definition](https://harth.build/resources/glossary/hot-water.md)
- [Building: Building Code Definition](https://harth.build/resources/glossary/building.md)
- [Construction Documents: Building Code Definition](https://harth.build/resources/glossary/construction-documents.md)
- [Registered Design Professional: Building Code Definition](https://harth.build/resources/glossary/registered-design-professional.md)

## 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](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.

### Source links

- [codes.iccsafe.org](https://codes.iccsafe.org/codes)

- [iccsafe.org](https://www.iccsafe.org/advocacy/code-adoption-maps/)

## Frequently asked questions

### What is the code definition of service water heating?

The International Energy Conservation Code (IECC) 2009 defines it in Definitions as: “Supply of hot water for purposes other than comfort heating.” 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 service water heating?

In this corpus the term is used across 5 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.

### What is service water heating?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IECC 2009 states, in Definitions: “Supply of hot water for purposes other than comfort heating.” It is defined in IECC 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 are the requirements for water heaters according to the Florida Building Code?

Building is a separate defined term. The IBC 2009 defines it as: “Any structure used or intended for supporting or sheltering any use or occupancy.” That is not the same as service water heating, which the IECC 2009 defines as “Supply of hot water for purposes other than comfort heating.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

---

- Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Fservice-water-heating%2F
- View this page in a browser: https://harth.build/resources/glossary/service-water-heating/
- All resources for agents: https://harth.build/llms.txt