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Hazard alert - Urgent warning to licensed plumbers working on hot water systems

Serious risks associated with working on hot water systems connected to uncontrolled heat sources

Following two significant incidents in Tasmania in as many years, Consumer, Building and Occupational Services (CBOS) is issuing an urgent warning to plumbers about the dangers of working on hot water systems connected to uncontrolled heat sources, such as wood heater water jackets and solar thermosiphon systems.

The Risk

Incorrect installation, alteration or repair of systems connected to uncontrolled heat sources can result in catastrophic system failure, including:

  • Superheated water and steam release
  • Explosion of water heating systems
  • Severe burns and scalding injuries
  • Significant property damage
  • Serious injury or death to occupants and workers.

Critical compliance requirement

Flow and return pipework associated with an uncontrolled heat source must never have provision for being isolated or capped off. This requirement is clearly set out in section 7 of AS/NZS 3500.4.

Any modification that prevents the safe circulation of water through an uncontrolled heat source can create extremely dangerous pressure and temperature conditions.

Know your limits

Plumbers undertaking work outside their level of competence risk causing serious injury or death to occupants. In addition to the safety risks, such work may constitute a breach of licence conditions and can result in substantial penalties, including fines and suspension or cancellation of a plumbing licence.

Stop and seek advice

If you are unsure about the design, installation or modification of a system involving an uncontrolled heat source, stop work and seek specialist advice before proceeding. Asking for help could save a life.

Recent Tasmanian incidents

For information including photographs depicting recent Tasmanian incidents, view the full hazard alert by clicking the link below:

Further information

For further information, please contact us by emailing cbos.info@justice.tas.gov.au or by phoning 1300 654 499.

Last updated: 18 Aug 2026

This page has been produced and published by the Consumer Building and Occupational Services Division of the Department of Justice. Although every care has been taken in production, no responsibility is accepted for the accuracy, completeness, or relevance to the user's purpose of the information. Those using it for whatever purpose are advised to verify it with the relevant government department, local government body or other source and to obtain any appropriate professional advice. The Crown, its officers, employees and agents do not accept liability however arising, including liability for negligence, for any loss resulting from the use of or reliance upon the information and/or reliance on its availability at any time.