Hydronic Heating System Install SWMS

Installing a hydronic heating system involves connecting a heat source (gas boiler, electric boiler or heat pump) to a distribution network of radiators, panel heaters or in-slab PEX coils, then pressure-testing, purging and commissioning the closed-loop circuit. The work combines licensed gas fitting, electrical connection, silver brazing of copper, hydrostatic pressure testing and confined access under suspended slabs or in plant rooms, which collectively meet the threshold for High Risk Construction Work under WHS Regulation 2011 r291 and the equivalent 2025 state instruments. A Safe Work Method Statement is mandatory before work commences because the task involves pressurised systems, hot work, energised electrical components and potential exposure to combustion products. This SWMS documents the hazards, controls and sign-on requirements needed to satisfy PCBU duties under s19 of the WHS Act and the consultation duties under s47–49, and provides the auditable record that principal contractors, plumbers and HVAC installers must retain for the life of the project plus the statutory retention period.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Elimination — Specify pre-insulated, factory-pressed press-fit hydronic pipework to eliminate site brazing on accessible runs and remove hot work from the scope wherever design permits.
2. 2Elimination — Design heat pump (electric) solution in lieu of combustion boiler where building services allow, removing gas leak, flue and combustion hazard entirely from the installation.
3. 3Substitution — Use cadmium-free silver brazing alloys (AS 1167.1) and low-fuming flux to replace cadmium-bearing rods where brazing cannot be eliminated.
4. 4Substitution — Substitute propylene glycol heat transfer fluid for ethylene glycol where freeze protection is required, reducing toxicity in event of leak or skin contact.
5. 5Engineering — Install local exhaust ventilation (LEV) capture hood within 300 mm of the brazing point delivering minimum 0.5 m/s capture velocity per AS/NZS 1715.
6. 6Engineering — Fit calibrated pressure relief valve and isolation cocks before hydrostatic test; pressurise in 100 kPa increments with witnessed hold periods documented on the test certificate.
7. 7Administrative — Apply lockout-tagout to boiler isolator, pump circuit and gas cock per AS/NZS 4836 before any electrical or pipework intervention, verified by second person.
8. 8Administrative — Hold daily pre-start briefing against this SWMS, gas test certificate (AS/NZS 5601.1) and electrical test sheet (AS/NZS 3000) with sign-on by every worker on task.
9. 9PPE — Issue flame-retardant long sleeves, AS/NZS 1337.1 shade 5 brazing goggles, leather gauntlets, AS/NZS 1716 P2 respirator and AS/NZS 2210.3 safety footwear.
10. 10PPE — Provide AS/NZS 1801 hard hat with chinstrap and AS/NZS 1800 hearing protection when working in plant rooms with operating circulating pumps above 85 dB(A).

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

On a mid-rise residential apartment refurbishment, a hydronic installer is fitting a 36 kW condensing gas boiler in a ground-floor plant room with in-slab PEX loops across six apartments. At the 6:45 am pre-start, the leading hand opens this SWMS on a tablet and walks the three-person crew through the hazard register, stopping on silver brazing fume because today's task includes 14 copper-to-copper joints on the primary flow header. The crew confirms the LEV trunk is positioned, cadmium-free rods are in the kit, and P2 respirators are fit-tested. The electrician notes that the boiler isolator is already locked out under his personal padlock and shows the test tag from yesterday. During brazing at joint seven, the apprentice reports the LEV capture velocity feels reduced; the leading hand stops the task, references the engineering control on the SWMS, repositions the hood to 250 mm from the joint and re-measures with the anemometer before resuming. After brazing, the team transitions to hydrostatic test — the SWMS prompts staged pressurisation in 100 kPa increments to 600 kPa with a 30-minute hold, witnessed and signed by the supervisor on the test certificate stapled to the SWMS sign-on sheet, which is then uploaded to the principal contractor's compliance portal before site exit.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• AS/NZS 5149 — Refrigerating systems; AS 1668 — Mechanical ventilation

Frequently asked questions