{"schemaVersion":1,"slug":"iec-water-heater-plan-mark","name":"Water heater plan mark","kind":"symbol","abbreviation":"WH","aliases":["hot water unit","storage water heater symbol","immersion heater outlet"],"category":"installation-communications","drawingTypes":["GA"],"referenceFamilies":["IEC"],"summary":"Plan mark for an electric water heater or hot-water storage unit with its electrical connection point.","description":["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."],"readingNotes":["Check tariff or control circuit notes.","Locate the isolator."],"drawingChecklist":["State element rating.","State tariff or control arrangement.","Show isolator."],"distinction":"A space heater warms air; a water heater warms stored water and is often on a controlled tariff.","facts":[{"label":"Graphic form","value":"Tank outline with heating mark"},{"label":"Control","value":"Thermostat, time switch or tariff relay"},{"label":"Exact standard graphic","value":"Not reproduced here; confirm the form against IEC 60617 and the project legend"}],"references":[{"sourceId":"iec-diagrams","relevance":"IEC graphical symbol context; independently drawn here."}],"related":["iec-electric-heater-plan-mark","iec-local-isolator-plan-mark","iec-time-switch-plan-mark"],"artwork":"s28-iec-water-heater-plan-mark","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEC","form":"Water heater","reference":"IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier."},"plainEnglish":{"title":"What does Water heater plan mark mean?","introduction":"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.","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.","drawings":"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.","terms":[{"name":"Terminal","meaning":"An identified point where a conductor connects."},{"name":"Rating","meaning":"A value stating the conditions for which equipment is specified."},{"name":"Schematic","meaning":"A drawing showing function and connections rather than physical appearance."}],"diagram":"flow","steps":["Identify the device and form","Read the connections and state","Check the equipment reference"],"caption":"A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.","sources":[{"label":"IEC graphical symbols for diagrams","url":"https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/"}],"detail":"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.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/iec-water-heater-plan-mark","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/iec-water-heater-plan-mark.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"iec-diagrams","title":"IEC graphical symbols for diagrams","publisher":"IEC","url":"https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/","type":"standard","scope":"IEC 60617 and related symbol-design publications. Full database access requires a subscription.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"IEC graphical symbol context; independently drawn here."}]}