# Water heater plan mark

Canonical URL: https://eloragrid.ai/symbols/iec-water-heater-plan-mark
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: WH
Drawing use: GA
Reference families: IEC

## Symbol convention

Convention: IEC
Form: Water heater
IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier.

Plan mark for an electric water heater or hot-water storage unit with its electrical connection point.

## In plain English

### What does Water heater plan mark mean?

Electric water heaters are drawn as a circle or rounded tank outline with a heating mark and the letters WH or HWU. The symbol locates the unit and its connection, often with an isolator alongside.

### A simple example

Water heaters may be on a controlled or off-peak tariff circuit, so the plan symbol is frequently tagged with the tariff or a time-switch link. The installer must route the circuit to the correct part of the board or meter. The symbol does not give capacity or element rating. These are scheduled with the plumbing equipment.

### What the drawings help you do

Check tariff or control circuit notes. Locate the isolator. A space heater warms air; a water heater warms stored water and is often on a controlled tariff.

### This particular reference

Plan mark for an electric water heater or hot-water storage unit with its electrical connection point. A space heater warms air; a water heater warms stored water and is often on a controlled tariff.

### Terms

- Terminal: An identified point where a conductor connects.
- Rating: A value stating the conditions for which equipment is specified.
- Schematic: A drawing showing function and connections rather than physical appearance.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/)


## What it represents

Electric water heaters are drawn as a circle or rounded tank outline with a heating mark and the letters WH or HWU. The symbol locates the unit and its connection, often with an isolator alongside.
Water heaters may be on a controlled or off-peak tariff circuit, so the plan symbol is frequently tagged with the tariff or a time-switch link. The installer must route the circuit to the correct part of the board or meter. The symbol does not give capacity or element rating. These are scheduled with the plumbing equipment.

## How to read it

- Check tariff or control circuit notes.
- Locate the isolator.

## Information to show or reference

- State element rating.
- State tariff or control arrangement.
- Show isolator.

## Important distinction

A space heater warms air; a water heater warms stored water and is often on a controlled tariff.

## Facts

- Graphic form: Tank outline with heating mark
- Control: Thermostat, time switch or tariff relay
- Exact standard graphic: Not reproduced here; confirm the form against IEC 60617 and the project legend

## Public references

- [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/) — IEC. IEC graphical symbol context; independently drawn here.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.