Thermostatic Mixing Valve Annual Test (AS 4032.3) SWMS

Thermostatic mixing valve annual testing covers the periodic testing, servicing and certification of thermostatic mixing valves — the valves that deliver temperature-controlled water to fixtures used for personal hygiene to prevent scalding. Thermostatic mixing valves are a critical scalding-prevention control whose performance can drift over time, so they must be tested and serviced at the required interval, and the delivered temperature verified, particularly in healthcare, aged-care and early-childhood settings where occupants are vulnerable. This document is written on the basis that thermostatic mixing valve testing is carried out by a licensed plumber competent in the testing, with the delivered temperature verified and the valve serviced and certified to the required regime.

Thermostatic mixing valves and their field testing and maintenance are covered by the AS 4032 series, with the heated water service installed to AS/NZS 3500.4, under which delivered water to sanitary fixtures used for personal hygiene must be temperature-limited — generally to 50 degrees, and to lower limits such as 45 degrees in early childhood, aged-care and healthcare settings — to prevent scalding. Annual testing verifies the valve still delivers within the required temperature, and the valve is serviced and certified. This document coordinates the temperature-verification, servicing, scalding and certification controls so the valve continues to protect against scalding.

Hazards identified

9 hazards covered, sorted by priority.

Control measures

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

1. 1Administrative: test the thermostatic mixing valve to the AS 4032 regime — verifying the delivered temperature at the fixture is within the required limit for the setting — and service the valve as required.
2. 2Engineering: set or adjust the valve as required so delivered water to sanitary fixtures used for personal hygiene is within the required maximum, and confirm it maintains a stable temperature.
3. 3Engineering: manage the stored energy and hot water during testing and servicing — isolating and controlling hot water so it does not scald.
4. 4Administrative: manage Legionella and system hygiene as part of the servicing, flushing where required so the system does not harbour growth.
5. 5Administrative: in healthcare and care settings, apply the infection-control and biological-hazard controls and coordinate with the facility so occupants are protected.
6. 6Engineering: verify the hot and cold connections after servicing to prevent cross-connection, and confirm the valve performs before it is returned to service.
7. 7Administrative: record the test result and the delivered temperature accurately, and certify the valve, scheduling the next test at the required interval.
8. 8Administrative: ensure the work is carried out and certified by an appropriately licensed plumber under the relevant state or territory plumbing licensing scheme, with the backflow, testing or other endorsement required and a compliance or test certificate issued where required.
9. 9Administrative: all workers must hold a valid White Card (General Construction Induction Training, CPCCWHS1001) where the work is construction work, with the plumbing competencies and any backflow, confined space or testing endorsements required for the work.
10. 10Administrative: conduct a pre-start toolbox talk covering the day's work, identified hazards, isolations, required PPE and emergency procedures, and record attendance in the consultation section.
11. 11Administrative: consult workers and any health and safety representatives on the work and its risks, record the consultation, and keep this document available at the workplace.
12. 12PPE: eye protection to AS/NZS 1337.1, hearing protection where required, gloves appropriate to the task, and Class I or Class II safety footwear with protective toecap to AS/NZS 2210.3.
13. 13Administrative: review and update this SWMS whenever the work scope changes, after any incident or near miss, when a worker or health and safety representative raises a concern, when new hazards are identified, or at minimum every 12 months.

Applicable Codes of Practice

Worked example

A licensed plumber competent in valve testing is engaged to carry out the annual testing of the thermostatic mixing valves in an aged-care facility. Each valve is tested to the AS 4032 regime, verifying the delivered temperature at the fixture is within the required limit for the care setting, such as 45 degrees, and serviced as required. Where a valve has drifted, it is adjusted so delivered water is within the required maximum and confirmed to maintain a stable temperature. The stored hot water is managed during testing and servicing so it does not scald. Legionella and system hygiene are managed as part of the servicing, with flushing where required. The infection-control and biological-hazard controls are applied and the work coordinated with the facility so residents are protected. The hot and cold connections are verified after servicing to prevent cross-connection, and each valve confirmed to perform before return to service. The test results and delivered temperatures are recorded accurately, the valves certified, and the next test scheduled. The records are retained.

Related legislation

• Model Work Health and Safety Act — primary duty of care; the duty to consult workers; the reckless-conduct offence; and notifiable-incident provisions, as enacted in each jurisdiction.
• Model Work Health and Safety Regulations — Section 291 high risk construction work and the SWMS preparation and review duties, and the confined space provisions where applicable, as enacted in each jurisdiction.
• The relevant plumbing and drainage standards AS/NZS 3500 (Parts 0–5), AS/NZS 1547 for on-site wastewater, the AS 4032 and AS 1357 valve standards, AS/NZS 2845.3 for backflow field testing, and AS 1851 for fire-system service, are called up by the state and territory plumbing and building safety legislation, together with the requirements of the relevant network utility.
• Plumbing work is licensed under each state and territory's plumbing licensing scheme, with backflow and testing accreditation required for that work, and compliance or test certification required for notifiable work; electrical work is carried out by a licensed electrician.
• Victoria operates under the Occupational Health and Safety Act 2004 and the Occupational Health and Safety Regulations 2017, with the high risk construction work and confined space provisions applying in place of the model instruments.

Frequently asked questions