AS/NZS 3500.4:2025
Plumbing and drainage – Part 4: Heated water services
Standard specifies the requirements for the design, installation and commissioning of heated water services using drinking water or rainwater or a combination thereof. It includes aspects of the installation from the valves on the cold-water inlet to any cold-water storage tank or water heater and the downstream fixtures and fittings. It applies to new installations as well as alterations, additions and repairs to existing installations.
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AS/NZS 3500.4:2025 Plumbing and drainage Heated water services
Preface
Section 1 Scope and general
1.1 Scope
1.2 Application
1.2.1 Australia
1.2.2 New Zealand
1.3 Normative references
1.4 Terms and definitions
1.5 Plastics abbreviations
1.6 Water chemistry
1.7 Pipe sizes
1.8 Velocity requirements
1.9 Pressure requirements
1.9.1 Available pressure
1.9.2 Pressure at outlets
1.9.3 Pressure losses
1.9.4 Pressure booster pumps
1.10 Flow rates
1.11 Water temperature
1.11.1 General
1.11.2 Storage temperature
Section 2 Materials and products
2.1 Scope of section
2.2 General
2.3 Pipes, fittings and connectors — General limitations
2.3.1 Pipes and fittings
2.3.2 Flexible hose assemblies
2.3.3 Semi-flexible hose assemblies
2.4 Metallic pipes and fittings
2.4.1 Heated water services
2.4.2 Limitations
2.5 Plastics pipes and fittings
2.5.1 Heated water services
2.5.2 Limitations
2.6 Safe tray and safe waste materials
2.6.1 Safe tray
2.6.2 Safe wastes
2.7 Joints
2.7.1 Flanged joints
2.7.2 Elastomeric seals
2.7.3 Silver brazing alloy
2.7.4 Filler rods for stainless steel joints
2.8 Miscellaneous materials
2.8.1 Concrete mix
2.8.2 Cement mortar
2.8.3 Water for concrete and mortar
2.8.4 Timber
2.8.5 External protective coatings
Section 3 Cross-connection and backflow prevention and thermostatic mixing valves
3.1 Scope of section
3.2 Cross-connection control and backflow prevention
3.3 Thermostatic mixing valves
Section 4 Installation of cold and heated water piping and controls
4.1 Scope of section
4.2 Installation of pipes and fittings
4.3 Proximity to other services
4.3.1 General
4.3.2 Electrical cables, gas pipes and other services
4.3.3 Crossover of underground services
4.4 Methods of jointing
4.4.1 General
4.4.2 Compression joints
4.4.3 Silver brazing
4.4.4 Flanged joints
4.4.5 Roll-grooved joints
4.4.6 Jointing of copper and copper alloy pipes
4.4.7 Jointing of stainless-steel pipe and fittings
4.4.8 Jointing of plastics pipes
4.5 Support and fixing above ground
4.5.1 General
4.5.2 Brackets, clips and hangers
4.5.3 Limitations on pipe supports
4.5.4 Spacing
4.5.5 Securing of pipes and fittings
4.6 Location of piping
4.6.1 Concealed piping
4.6.2 Protection during building construction
4.6.3 Floor or roof penetrations
4.6.4 Provision for movement of encased piping
4.7 Bedding and backfill
4.8 Contaminated areas — Installation
4.9 Corrosive areas
4.10 Depth of cover
4.10.1 Depth of cover in public areas
4.10.2 Depth of cover in private areas
4.11 Protection against freezing
4.11.1 Requirement for protection
4.11.2 Piping located outside buildings
4.11.3 Pipes located on metal roofs
4.11.4 Pipes located inside buildings
4.11.5 Insulation of piping and fittings
4.12 Cold-water piping and storage tanks
4.12.1 General
4.12.2 Cold-water storage tank
4.12.3 Safe tray for cold-water storage tanks
4.12.4 Support for separately mounted cold-water storage tanks
4.13 Installation of heated water services
4.13.1 Design and installation
4.13.2 Identification of piping
4.13.3 Provision for expansion
4.13.4 Gradient
4.13.5 Maximum rise of heated water supply pipes
4.13.6 Shower assemblies
4.13.7 Venting of secondary circuit
4.13.8 Recirculation of cold water
Section 5 Installation of water heaters — General requirements
5.1 Scope of section
5.2 Water heaters
5.2.1 Selection of anode
5.2.2 Working pressure
5.3 Location
5.3.1 Placement
5.3.2 Accessibility and clearances
5.3.3 Ventilation and fluing
5.4 Protection against damage from leaking water
5.4.1 Concealed water storage tanks
5.4.2 Unconcealed water storage tanks
5.4.3 Safe tray construction
5.4.4 Safe wastes
5.4.5 Placement of water heater or cold-water storage tank on a safe tray
5.5 Support
5.5.1 Support of water storage tanks installed in a roof
5.5.2 Support of water heaters or water storage tanks installed above a roof
5.5.3 Support of water heaters or water storage tanks installed other than in a roof space or above a roof
5.5.4 Seismic restraints
5.6 Corrosion prevention and weather protection
5.6.1 Water heater base — Corrosion avoidance
5.6.2 Weather protection of externally installed water heaters
5.7 Connections to water heaters
5.8 Pressure relief and venting of water heaters and containers
5.9 Valves and expansion vessels
5.9.1 General
5.9.2 Required set pressure of valves (for unvented water heaters)
5.9.3 Set pressure of expansion vessels
5.9.4 Installation of valves and expansion vessels
5.10 Multiple installations of pressure-type storage water heaters
5.10.1 General
5.10.2 Balanced flow conditions
5.10.3 Location and sizing of control valves and expansion vessels on the cold-water supply
5.11 Temperature/pressure-relief valve and expansion control valve drain lines
5.11.1 Size and material
5.11.2 Interconnection of drain lines
5.11.3 Installation
5.11.4 Common stack discharge
5.11.5 Tundish drain lines
5.11.6 Areas subject to freezing
5.12 Vent pipes
5.12.1 Installation
5.12.2 Termination of vent pipe
5.12.3 Cold-water storage tank-fed water heaters (other than side-fed types)
5.12.4 Vented storage water heaters, inlet pressure-controlled
Section 6 Installation of solar water heaters
6.1 Scope of section
6.2 Application of section (New Zealand only)
6.3 General installation requirements
6.3.1 Sizing and solar performance
6.3.2 Location
6.3.3 Structural integrity
6.3.4 Water hardness and dissolved solids
6.3.5 Collector circuit
6.3.6 Flow and return pipes and fittings
6.3.7 Corrosion resistance
6.3.8 Entrapped air
6.3.9 Over-temperature protection
6.3.10 Pressure and temperature relief
6.3.11 Drain lines
6.3.12 Unintentional circulation
6.3.13 Mounting
6.3.14 Supplementary heating
6.3.15 Penetrations through roof cladding
6.4 Installation of solar water heater storage containers
6.4.1 General
6.4.2 Thermosiphon systems
6.4.3 Support
6.4.4 Safe trays
6.4.5 Auxiliary water heating
6.5 Installation of collectors
6.5.1 Positioning
6.5.2 Precautions
6.6 Solar water heaters with remote containers
6.6.1 Pumps and controllers
6.6.2 Pump and controller installation
Section 7 Uncontrolled heat sources
7.1 Scope of section
7.2 Water heaters with uncontrolled energy source
7.2.1 Installation
7.2.2 Supplementary external heating
7.2.3 Provision for drainage
Section 8 Energy efficiency
8.1 Scope of section
8.2 Thermal insulation
8.2.1 Piping associated with storage water heaters
8.2.2 Other piping for heated water systems
8.3 Protection of insulation
8.3.1 Insulation exposed to the weather
8.3.2 Protection of thermal insulation on buried piping
8.4 Heat traps
8.5 R-value calculations
Section 9 Testing and commissioning
9.1 Scope of section
9.2 Flushing
9.3 Testing
9.4 Commissioning
9.5 Heated water circulating system diagram
9.6 Operating instructions
Section 10 Sizing and installation of circulatory heated water reticulation
10.1 Scope of section
10.2 Temperature requirements
10.3 Flow requirements
10.3.1 General
10.3.2 Flow rates
10.3.3 Loading units
10.3.4 Continuous demand outlets
10.3.5 Probable simultaneous demand
10.3.6 Probable simultaneous flow rate
10.4 Maximum pressure requirements
10.4.1 Maximum pressure within buildings
10.4.2 Maximum differential
10.5 Pressure requirements for circulatory heated water systems
10.6 Velocity requirements
10.6.1 Circulating pumps
10.6.2 Velocity, pressure and temperature
10.7 Expansion of heated water
10.8 Air elimination
10.8.1 General
10.8.2 Air elimination valves
10.9 Location of circulatory piping
10.9.1 General
10.9.2 Branch off-takes
10.9.3 Branch off-take with meter
10.9.4 Proximity to cold-water piping
10.10 Isolating valves
10.10.1 General
10.10.2 Location
10.10.3 Multiple apartments, dwellings and secure areas
10.11 Balancing valves
10.11.1 General
10.11.2 Commissioning
Appendix A (informative) Water analysis
Appendix B (informative) Demonstrating products and materials are fit for purpose
Appendix C (normative) Internal pipe diameters
Appendix D (informative) Preferred pipe sizes for non-circulatory typical single-storey household installations
Appendix E (informative) Recommendations for the installation of unrated solar heated water supply systems
Appendix F (informative) Recommendations for the installation of close-coupled and integral solar heated water supply systems on roofs
Appendix G (informative) Solar heated water supply systems — Suggested component sizes (custom-built systems)
Appendix H (informative) Estimation of shading of collectors
Appendix I (informative) Effect of inclination and orientation on system performance
Appendix J (informative) Map of regional basic design wind speeds
Appendix K (normative) Australian climate regions
Appendix L (normative) New Zealand climate regions
Appendix M (informative) Operation and maintenance
Appendix N (normative) Provision for expansion and contraction
Appendix O (informative) Estimation of probable simultaneous demand for residential buildings from the total of loading units
Appendix P (normative) Sizing of expansion vessels in mains pressure systems
Appendix Q (informative) Sizing of branches from circulatory heated water systems
Bibliography
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References
Installation of PVC pipe systems
Plumbing and drainage – Part 1: Water services
Testing of products for use in contact with drinking water
Heated water systems - Calculation of energy consumption
Specification for copper tubes for water, gas, and sanitation
Seismic performance of engineering systems in buildings
Installation of low pressure thermal storage electric water heaters with copper cylinders (open-vented systems)
Installation of thermal storage electric water heaters: valve-vented systems
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AS/NZS 3500.4:2025 Plumbing and drainage Heated water services
Preface
Section 1 Scope and general
1.1 Scope
1.2 Application
1.2.1 Australia
1.2.2 New Zealand
1.3 Normative references
1.4 Terms and definitions
1.5 Plastics abbreviations
1.6 Water chemistry
1.7 Pipe sizes
1.8 Velocity requirements
1.9 Pressure requirements
1.9.1 Available pressure
1.9.2 Pressure at outlets
1.9.3 Pressure losses
1.9.4 Pressure booster pumps
1.10 Flow rates
1.11 Water temperature
1.11.1 General
1.11.2 Storage temperature
Section 2 Materials and products
2.1 Scope of section
2.2 General
2.3 Pipes, fittings and connectors — General limitations
2.3.1 Pipes and fittings
2.3.2 Flexible hose assemblies
2.3.3 Semi-flexible hose assemblies
2.4 Metallic pipes and fittings
2.4.1 Heated water services
2.4.2 Limitations
2.5 Plastics pipes and fittings
2.5.1 Heated water services
2.5.2 Limitations
2.6 Safe tray and safe waste materials
2.6.1 Safe tray
2.6.2 Safe wastes
2.7 Joints
2.7.1 Flanged joints
2.7.2 Elastomeric seals
2.7.3 Silver brazing alloy
2.7.4 Filler rods for stainless steel joints
2.8 Miscellaneous materials
2.8.1 Concrete mix
2.8.2 Cement mortar
2.8.3 Water for concrete and mortar
2.8.4 Timber
2.8.5 External protective coatings
Section 3 Cross-connection and backflow prevention and thermostatic mixing valves
3.1 Scope of section
3.2 Cross-connection control and backflow prevention
3.3 Thermostatic mixing valves
Section 4 Installation of cold and heated water piping and controls
4.1 Scope of section
4.2 Installation of pipes and fittings
4.3 Proximity to other services
4.3.1 General
4.3.2 Electrical cables, gas pipes and other services
4.3.3 Crossover of underground services
4.4 Methods of jointing
4.4.1 General
4.4.2 Compression joints
4.4.3 Silver brazing
4.4.4 Flanged joints
4.4.5 Roll-grooved joints
4.4.6 Jointing of copper and copper alloy pipes
4.4.7 Jointing of stainless-steel pipe and fittings
4.4.8 Jointing of plastics pipes
4.5 Support and fixing above ground
4.5.1 General
4.5.2 Brackets, clips and hangers
4.5.3 Limitations on pipe supports
4.5.4 Spacing
4.5.5 Securing of pipes and fittings
4.6 Location of piping
4.6.1 Concealed piping
4.6.2 Protection during building construction
4.6.3 Floor or roof penetrations
4.6.4 Provision for movement of encased piping
4.7 Bedding and backfill
4.8 Contaminated areas — Installation
4.9 Corrosive areas
4.10 Depth of cover
4.10.1 Depth of cover in public areas
4.10.2 Depth of cover in private areas
4.11 Protection against freezing
4.11.1 Requirement for protection
4.11.2 Piping located outside buildings
4.11.3 Pipes located on metal roofs
4.11.4 Pipes located inside buildings
4.11.5 Insulation of piping and fittings
4.12 Cold-water piping and storage tanks
4.12.1 General
4.12.2 Cold-water storage tank
4.12.3 Safe tray for cold-water storage tanks
4.12.4 Support for separately mounted cold-water storage tanks
4.13 Installation of heated water services
4.13.1 Design and installation
4.13.2 Identification of piping
4.13.3 Provision for expansion
4.13.4 Gradient
4.13.5 Maximum rise of heated water supply pipes
4.13.6 Shower assemblies
4.13.7 Venting of secondary circuit
4.13.8 Recirculation of cold water
Section 5 Installation of water heaters — General requirements
5.1 Scope of section
5.2 Water heaters
5.2.1 Selection of anode
5.2.2 Working pressure
5.3 Location
5.3.1 Placement
5.3.2 Accessibility and clearances
5.3.3 Ventilation and fluing
5.4 Protection against damage from leaking water
5.4.1 Concealed water storage tanks
5.4.2 Unconcealed water storage tanks
5.4.3 Safe tray construction
5.4.4 Safe wastes
5.4.5 Placement of water heater or cold-water storage tank on a safe tray
5.5 Support
5.5.1 Support of water storage tanks installed in a roof
5.5.2 Support of water heaters or water storage tanks installed above a roof
5.5.3 Support of water heaters or water storage tanks installed other than in a roof space or above a roof
5.5.4 Seismic restraints
5.6 Corrosion prevention and weather protection
5.6.1 Water heater base — Corrosion avoidance
5.6.2 Weather protection of externally installed water heaters
5.7 Connections to water heaters
5.8 Pressure relief and venting of water heaters and containers
5.9 Valves and expansion vessels
5.9.1 General
5.9.2 Required set pressure of valves (for unvented water heaters)
5.9.3 Set pressure of expansion vessels
5.9.4 Installation of valves and expansion vessels
5.10 Multiple installations of pressure-type storage water heaters
5.10.1 General
5.10.2 Balanced flow conditions
5.10.3 Location and sizing of control valves and expansion vessels on the cold-water supply
5.11 Temperature/pressure-relief valve and expansion control valve drain lines
5.11.1 Size and material
5.11.2 Interconnection of drain lines
5.11.3 Installation
5.11.4 Common stack discharge
5.11.5 Tundish drain lines
5.11.6 Areas subject to freezing
5.12 Vent pipes
5.12.1 Installation
5.12.2 Termination of vent pipe
5.12.3 Cold-water storage tank-fed water heaters (other than side-fed types)
5.12.4 Vented storage water heaters, inlet pressure-controlled
Section 6 Installation of solar water heaters
6.1 Scope of section
6.2 Application of section (New Zealand only)
6.3 General installation requirements
6.3.1 Sizing and solar performance
6.3.2 Location
6.3.3 Structural integrity
6.3.4 Water hardness and dissolved solids
6.3.5 Collector circuit
6.3.6 Flow and return pipes and fittings
6.3.7 Corrosion resistance
6.3.8 Entrapped air
6.3.9 Over-temperature protection
6.3.10 Pressure and temperature relief
6.3.11 Drain lines
6.3.12 Unintentional circulation
6.3.13 Mounting
6.3.14 Supplementary heating
6.3.15 Penetrations through roof cladding
6.4 Installation of solar water heater storage containers
6.4.1 General
6.4.2 Thermosiphon systems
6.4.3 Support
6.4.4 Safe trays
6.4.5 Auxiliary water heating
6.5 Installation of collectors
6.5.1 Positioning
6.5.2 Precautions
6.6 Solar water heaters with remote containers
6.6.1 Pumps and controllers
6.6.2 Pump and controller installation
Section 7 Uncontrolled heat sources
7.1 Scope of section
7.2 Water heaters with uncontrolled energy source
7.2.1 Installation
7.2.2 Supplementary external heating
7.2.3 Provision for drainage
Section 8 Energy efficiency
8.1 Scope of section
8.2 Thermal insulation
8.2.1 Piping associated with storage water heaters
8.2.2 Other piping for heated water systems
8.3 Protection of insulation
8.3.1 Insulation exposed to the weather
8.3.2 Protection of thermal insulation on buried piping
8.4 Heat traps
8.5 R-value calculations
Section 9 Testing and commissioning
9.1 Scope of section
9.2 Flushing
9.3 Testing
9.4 Commissioning
9.5 Heated water circulating system diagram
9.6 Operating instructions
Section 10 Sizing and installation of circulatory heated water reticulation
10.1 Scope of section
10.2 Temperature requirements
10.3 Flow requirements
10.3.1 General
10.3.2 Flow rates
10.3.3 Loading units
10.3.4 Continuous demand outlets
10.3.5 Probable simultaneous demand
10.3.6 Probable simultaneous flow rate
10.4 Maximum pressure requirements
10.4.1 Maximum pressure within buildings
10.4.2 Maximum differential
10.5 Pressure requirements for circulatory heated water systems
10.6 Velocity requirements
10.6.1 Circulating pumps
10.6.2 Velocity, pressure and temperature
10.7 Expansion of heated water
10.8 Air elimination
10.8.1 General
10.8.2 Air elimination valves
10.9 Location of circulatory piping
10.9.1 General
10.9.2 Branch off-takes
10.9.3 Branch off-take with meter
10.9.4 Proximity to cold-water piping
10.10 Isolating valves
10.10.1 General
10.10.2 Location
10.10.3 Multiple apartments, dwellings and secure areas
10.11 Balancing valves
10.11.1 General
10.11.2 Commissioning
Appendix A (informative) Water analysis
Appendix B (informative) Demonstrating products and materials are fit for purpose
Appendix C (normative) Internal pipe diameters
Appendix D (informative) Preferred pipe sizes for non-circulatory typical single-storey household installations
Appendix E (informative) Recommendations for the installation of unrated solar heated water supply systems
Appendix F (informative) Recommendations for the installation of close-coupled and integral solar heated water supply systems on roofs
Appendix G (informative) Solar heated water supply systems — Suggested component sizes (custom-built systems)
Appendix H (informative) Estimation of shading of collectors
Appendix I (informative) Effect of inclination and orientation on system performance
Appendix J (informative) Map of regional basic design wind speeds
Appendix K (normative) Australian climate regions
Appendix L (normative) New Zealand climate regions
Appendix M (informative) Operation and maintenance
Appendix N (normative) Provision for expansion and contraction
Appendix O (informative) Estimation of probable simultaneous demand for residential buildings from the total of loading units
Appendix P (normative) Sizing of expansion vessels in mains pressure systems
Appendix Q (informative) Sizing of branches from circulatory heated water systems
Bibliography
AS/NZS 3500.4:2025
Online Library subscription information
Online library subscriptions provide a cost-effective solution for organisations of any size to access the latest standards, offering 24/7 access to a personalised catalogue. The service ensures subscribers have have the most up-to-date version of selected standards, incluing automatic updates for any amendments or versions. Pricing is dependent on the chosen standards and the number of concurrent users, with discounts applied from the standards PDF price. For customised subscriptions or further inquiries, contact the Online Library team.