Continuous Flow / Instantaneous Gas Hot Water SWMS
Safe work method statement for the installation and commissioning of continuous flow instantaneous gas hot water units including flue sizing, gas line modification, and hot water delivery temperature compliance.
SWMS variants reference your state’s WHS legislation. Instant download after payment.
The installation and commissioning of continuous flow (instantaneous) gas hot water units is a high-skill plumbing and gasfitting activity that combines pressurised gas work, electrical interfacing, flue gas management, and hot water tempering compliance. This SWMS covers the full scope of works including unit mounting, gas line modification or extension, flue sizing and termination, water connection, electrical isolation interface, commissioning, and verification of delivery temperature in accordance with AS/NZS 3500.4 and AS/NZS 5601.1.
Under the model Work Health and Safety Act 2011 and WHS Regulation 2025, a Person Conducting a Business or Undertaking (PCBU) must manage risks to health and safety so far as is reasonably practicable. While instantaneous gas hot water installation is not classified as High Risk Construction Work under Regulation 291, a documented SWMS is the most effective means of demonstrating compliance with the general risk management duties under Regulations 32–38, and is frequently required by principal contractors, gas network operators, and clients before site access is granted.
This SWMS has been prepared by a Certified Industrial Hygienist and aligns with the Gas Installation Standard AS/NZS 5601.1:2022, the Plumbing Code of Australia, and state-based gasfitting licensing requirements. It addresses the specific hazards of LPG and natural gas work, hot surface burns, working at heights for flue terminations, and confined spaces where units are installed in roof voids or service cupboards.
Hazards identified
12 hazards covered, sorted by priority.
Catastrophic burns, fatality, structural damage from deflagration
CO poisoning of occupants, potentially fatal at concentrations >800 ppm
Second-degree burns within 1 second at 60°C delivery temperature
Fall injuries including fractures, head trauma
Electrocution, cardiac arrest, secondary fall injury
Musculoskeletal injury, shoulder and lumbar strain
Oxygen deficiency, heat stress, restricted egress in emergency
Contact burns to hands and forearms
Metal fume fever, respiratory irritation
Arc eye, skin burns, long-term ocular damage
Sprains, fractures from falls on wet surfaces
Lacerations to hands requiring sutures
Control measures
Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.
- 1Only licensed gasfitters (Type A appliance work licence in the relevant state/territory) to perform gas line modification and commissioning, with licence number recorded on the SWMS sign-on register
- 2Isolate gas supply at the meter/cylinder and conduct a pressure decay test on the modified gas line in accordance with AS/NZS 5601.1 Section 4.11 before introducing gas; verify with electronic manometer (not soap solution alone)
- 3Calculate flue sizing using manufacturer specifications and AS/NZS 5601.1 clearances, ensuring termination is at least 500 mm from openings, 1.5 m from mechanical air intakes, and not under eaves where prohibited by the appliance certification
- 4Install an approved tempering valve (AS/NZS 4032.3) to limit delivery temperature to 50°C at sanitary fixtures (45°C in early childhood, aged care, healthcare facilities per PCA Part B2), and verify with calibrated thermometer at the most distant outlet
- 5Use a fall-arrest harness anchored to a rated point, or scaffold/EWP, for any work above 2 m including external flue terminations; ladders to be used only for access, not as a work platform for brazing
- 6De-energise and lock out any electrical supply within 500 mm of the work area; confirm zero energy with a tested-and-proven voltage tester before commencing mounting
- 7Two-person lift or use of a mechanical lifting aid for unit installation above shoulder height; pre-fit the mounting bracket to wall studs or masonry anchors rated for 4× the unit weight
- 8Ventilate any confined or restricted space prior to entry, monitor with a 4-gas detector (O₂, LEL, CO, H₂S) where combustion residues or LPG accumulation is foreseeable, and maintain a standby person at the access point
- 9Wear AS/NZS 1338.1 shade 5 brazing goggles, leather gauntlets, long-sleeved cotton drill, and use local exhaust ventilation or work in well-ventilated areas when silver brazing; never use cadmium-bearing filler rods
- 10Conduct a final combustion analysis using a calibrated flue gas analyser to confirm CO/CO₂ ratio is within manufacturer specification (typically <0.004 ratio) before signing off commissioning
- 11Place absorbent matting and drip trays beneath water connections; mop up spillage immediately and place wet floor signage during commissioning
- 12Wear cut-resistant gloves (AS/NZS 2161.3 Level C minimum) when handling flue cowls, flashing, and stainless cladding; deburr all cut edges
Applicable Codes of Practice
Mandatory standard for all gas line work, flue sizing, ventilation, and appliance commissioning
Governs hot water delivery temperatures, tempering valve installation, and pipe sizing
Specifies tempering valve performance for scald prevention compliance
Section 26A approved code applicable to ventilation and access provisions during installation
Section 26A approved code applying to flue terminations and elevated unit mounting above 2 m
Section 26A approved code establishing the hierarchy of control applied throughout this SWMS
Applies to lifting and overhead mounting of the unit
Applies where units are installed in roof voids, under-stair spaces, or other restricted access areas
Who this is for
- →Licensed plumbing and gasfitting contractors installing residential and light-commercial continuous flow units
- →Plumbing PCBUs tendering for principal contractor work where SWMS submission is a prerequisite for site access
- →Hot water specialist businesses replacing storage units with instantaneous systems under retrofit programs
- →Apprentice supervisors who require a documented method statement to demonstrate adequate supervision under WHS Regulation 39
- →Self-employed gasfitters servicing real estate property managers and home warranty insurers
- →Maintenance plumbers performing like-for-like swap-outs on existing instantaneous units
What you receive
- ✓Fully editable Microsoft Word (DOCX) SWMS template with company branding placeholders
- ✓State-specific legislation schedule covering NSW, VIC, QLD, SA, WA, TAS, ACT and NT WHS/OHS variations
- ✓Pre-populated hazard register with 12 identified hazards, risk ratings, and hierarchy-of-control responses
- ✓Worker sign-on register with licence number, induction date, and acknowledgement fields
- ✓Pre-start checklist for gas pressure testing, flue verification, and tempering valve commissioning
- ✓Combustion analysis and commissioning record sheet aligned with AS/NZS 5601.1
- ✓Free lifetime updates when referenced standards or WHS Regulations are amended
Worked example
A licensed gasfitter from a three-person plumbing business is engaged to replace a failed 170 L electric storage unit with a 26 L/min continuous flow natural gas unit at a two-storey residence in suburban Melbourne. The unit is to be wall-mounted externally at 1.8 m above ground, with the flue terminating 600 mm above the unit. Before commencing, the gasfitter reviews this SWMS with their apprentice, both sign on, and the apprentice's licence stage and supervision ratio are recorded. The team isolates the gas at the meter, performs a pressure decay test on the upgraded 20 mm copper gas line, conducts the unit mounting using a two-person lift from a mobile scaffold, and commissions the system. They install an AS/NZS 4032.3 tempering valve set to 50°C, verify delivery temperature at the master bathroom basin (the most distant outlet) with a calibrated digital thermometer, and complete a flue gas analysis showing a CO/CO₂ ratio of 0.0021 — within manufacturer tolerance. The completed SWMS, sign-on register, and commissioning sheet are filed with the job and a copy provided to the homeowner, satisfying both WHS Regulation 2025 documentation duties and the Victorian Building Authority compliance certificate requirements.
Related legislation
- Work Health and Safety Act 2011 (Cth model)
- Work Health and Safety Regulation 2025
- Gas Safety Act 1997 (Vic) and equivalent state gas safety legislation
- Plumbing and Drainage Act 2018 (NSW) and state equivalents
- National Construction Code 2022 - Plumbing Code of Australia
- Electrical Safety Act 2002 (where electrical interfacing is undertaken)
- Environment Protection Act 2017 (refrigerant and combustion emissions where applicable)
Frequently asked questions
Is a SWMS legally required for instantaneous gas hot water installation if it isn't High Risk Construction Work?
While Regulation 291 of the WHS Regulation 2025 only mandates a SWMS for the 18 categories of HRCW, the general risk management duties under Regulations 32–38 require a PCBU to identify, assess, and control risks. A documented SWMS is the most defensible means of demonstrating compliance, and most principal contractors and government clients contractually require one regardless of HRCW classification.
Does this SWMS cover both natural gas and LPG installations?
Yes. The hazard register and controls address both fuel gases. LPG-specific considerations (heavier-than-air vapour accumulation, cylinder handling, regulator selection) are flagged in the controls section, and the document references AS/NZS 5601.1 which governs both fuels.
Who can sign off the commissioning section of this SWMS?
Only a person holding a current Type A gas appliance work licence (or state equivalent such as the Victorian Plumbing Industry Commission gasfitting licence) may legally commission a gas appliance and sign the commissioning record. The SWMS includes a dedicated licence number field for this purpose.
How often should this SWMS be reviewed?
Per Regulation 38, a SWMS must be reviewed when the work changes, an incident occurs, a control measure is found to be inadequate, or a HSR requests review. As a baseline, we recommend annual review, plus immediate review whenever AS/NZS 5601.1 or AS/NZS 3500.4 is amended — our update service notifies you when this occurs.
Does the SWMS address the new 50°C delivery temperature requirements?
Yes. The controls and commissioning record reflect AS/NZS 3500.4 and PCA Part B2 requirements: 50°C maximum at sanitary fixtures in residential settings and 45°C in early childhood, aged care, primary/secondary schools, and healthcare facilities, achieved via an approved AS/NZS 4032.3 tempering valve.
Can my apprentice work from this SWMS unsupervised?
No. Apprentices must work under the supervision ratio prescribed by their state licensing authority. The SWMS sign-on register includes an apprentice supervision field, and the controls explicitly require licensed gasfitter sign-off for all gas pressure testing and commissioning activities.