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AS/NZS 3500.4:2021


Plumbing and drainage, Part 4: Heated water services

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Sets out 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, and including, the valve(s) 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.
Published: 28/05/2021
Pages: 143
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Table of contents
Cited references
Content history
Table of contents
About this publication
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 General Pump control
1.10 Flow rates
1.11 Water temperature
1.11.1 General
1.11.2 Storage temperature
2 Materials and products
2.1 Scope of section
2.2 General
2.3 Pipes and fittings — General limitations
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 Copper and copper alloys Stainless steel
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 Timber in Australia Timber in New Zealand
2.8.5 External protective coatings
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
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 General Above-ground services Below ground — Electrical cables and gas pipes Below ground — Communications
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 Joints Taps and valves
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 Jointing of piping up to and including DN 25 Jointing of piping larger than DN 25
4.4.8 Jointing of plastics pipes PVC-C Other 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 Walls Chases, ducts or conduits Under concrete slabs
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 General Pipes in unheated roof spaces Pipes adjacent to external walls
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 General Water storage tank capacity Flow capacity Cold water storage tank overflow Position of cold water storage tanks
4.12.3 Safe tray for cold water storage tanks
4.12.4 Support for separately mounted cold water storage tanks Platform Spacing between cold water storage tank and safe tray
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
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 Sizes of safe wastes Safe waste construction Safe waste installation
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 Individual water heaters Multiple relief valves
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 Storage water heaters Heat exchange water heaters and boiling water units
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
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 Shade Commercial solar collector orientation Residential solar collector orientation Inclination Provision for removal of collector
6.5.2 Precautions Avoidance of damage Frost-prone areas Hail-prone areas
6.6 Solar water heaters with remote containers
6.6.1 Pumps and controllers
6.6.2 Pump and controller installation
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
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
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
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 Return pipe Sizing 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 General Length and capacity of dead leg 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
A.1 Water analysis
A.2 Conductivity and total dissolved solids
Appendix B
B.1 General
B.2 Australia
B.3 New Zealand
Appendix C
Appendix D
Appendix E
E.1 General
E.2 Volumetric storage capacity
E.3 Recommended operating temperature
E.4 Temperature/pressure-relief valve
E.5 Collector/container size ratio
E.5.1 Normal conditions
E.5.2 Non-optimum conditions
E.6 Components
E.7 Claimed performance
Appendix F
F.1 General
F.2 Support
F.2.1 “With pitch” installations
F.2.2 “Against pitch” installations
F.2.3 “Cross-pitch” installations
F.3 Points to note
Appendix G
G.1 Anticipated solar fraction
G.2 Solar radiation data
Appendix H
H.1 General
H.2 Sun locator
H.3 Approximate method of determining solar altitude
Appendix I
Appendix J
Appendix K
K.1 Scope
K.2 Climate zones
Appendix L
L.1 General
L.2 Climate regions
L.3 Frost areas
Appendix M
M.1 Scope
M.2 General
M.3 Maintenance of heated water services
Appendix N
N.1 Scope
N.2 General
N.3 Calculating thermal length change
N.4 Provision for expansion
N.5 Calculating the offset length
N.5.1 Example 1
N.5.2 Example 2
N.6 Offsets in bends with two anchor points
N.7 Expansion loops
N.8 Calculating the offset length for an expansion loop or U-bend
N.8.1 Example 3
N.9 Branch off-takes
N.9.1 Example 4
N.10 Branch off-takes in ducts
Appendix O
Appendix P
Appendix Q
Q.1 Scope
Q.2 General
Q.3 Worked example
Cited references in this standard
NZS 4219
Seismic performance of engineering systems in buildings
NZS 4607
Installation of thermal storage electric water heaters: valve-vented systems
NZS 4603
Installation of low pressure thermal storage electric water heaters with copper cylinders (open-vented systems)
NZS 3501
Specification of copper tubes for water, gas and sanitation
Plumbing and drainage, Part 1: Water services
Content history
[Available Superseded]
[Available Superseded]
[Available Superseded]
[Available Superseded]
[Available Superseded]