Part B2 Heated water services
Introduction to this Part
This Part sets out the requirements for the design, construction, installation, replacement, repair, alteration and maintenance of any part of a heated water service of a property that is connected to the drinking water supply. It covers from the point of connection to the points of discharge.
The Objective of this Part is to—
- safeguard people from illness, injury or loss (including loss of amenity) due to the failure of a heated water installation; and
- ensure that a heated water installation is suitable; and
- conserve water; and
- safeguard the environment; and
- reduce greenhouse gas emissions; and
- safeguard public and private infrastructure; and
- ensure that a heated water installation is designed and is capable of being maintained so that throughout its serviceable life it will continue to satisfy Objectives (a) to (f).
- minimises any adverse impact on building occupants, the Network Utility Operator's infrastructure, property and the environment; and
- facilitates the conservation of water.
To reduce greenhouse gas emissions, to the degree necessary, a heated water service is to—
- be capable of efficiently using energy; and
- obtain its heating energy from—
- a low greenhouse gas intensity energy source; or
- an on-site renewable energy source; or
- another process as reclaimed energy.
The greenhouse gas intensity of energy sources vary. For example, natural gas has a low greenhouse gas intensity compared with electricity generated from coal.
BP2.1 Water supply
BP2.3 Design, construction and installation
A heated water service must ensure the following:
Heated water is provided at appropriate flow rates and temperatures for fixtures and appliances to function.
Access for maintenance of mechanical components and operational controls.
The system, appliances and devices can be isolated for testing and maintenance.
BP2.4 Pressure relief and temperature limitation
Containers used for producing and/or storing heated water must—
relieve excessive pressure; and
limit temperatures to avoid flash steam production in the event of rupture.
BP2.5 Legionella control
Heated water must be stored and delivered under conditions which avoid the likelihood of the growth of Legionella bacteria.
BP2.6 Energy use and source
A heated water service, including any associated distribution system and components, must ensure the efficient use of energy and water.
Excessive 'dead water' draw-off, i.e. where cooled water from the supply pipe is drained off prior to delivery of heated water, can result in water and energy wastage.
To improve the efficiency of heated water systems, the design should consider factors such as the number of outlets, their purpose and expected typical usage, and the distance between the water heater and each of the outlets. The water heatershould be positioned nearest to the most used outlets, or installed to provide consistent coverage of the building. Where this is not viable, the use of multiple water heaters or flow and return pipe loop may need to be considered.
Features in BP2.6(1) must be appropriate to the following:
The heated water service and its usage.
The geographic location of the building.
The location of the heated water service.
The energy or water source.
BP2.6(2) permits the energy source of the heated water service to be considered. This means that the net energy obtained from renewable energy sources such as solar, geothermal, wind, and biofuels may be considered as 'free' energy in calculating the energy consumption. Similarly, heat reclaimed from another 'free' source such as a by-product from co-generation type processes as well as other industrial processes, which could otherwise be rejected from the building, could be considered as 'free' energy in calculating the energy consumption.
A heated water service, including any associated distribution system and components, must obtain heating energy from one, or a combination, of the following:
A source that has a greenhouse gas intensity up to and including 100 g CO2-e/MJ of thermal energy load.
An on-site renewable energy source.
Another process as reclaimed energy.
- The intent of BP2.6(3) is to constrain the use of a high greenhouse gas intensity source of energy. It does not prevent the use of electricity because the greenhouse gas intensity is related to the thermal load rather than the energy consumption which is covered by BP2.6(2).
- For the purposes of BP2.6(3) the renewable energy must be on-site (not GreenPower) and includes, but is not limited to, solar, wind, hydroelectric, wave action, and geothermal.
BV2.1 Greenhouse gas intensity of a water heater
annual amount of energy consumed from that energy source; and
emission factor of—
if the energy source is electricity, 253 g CO2-e/MJ; or
if the energy source is liquefied petroleum gas, 65 g CO2-e/MJ; or
if the energy source is natural gas, 61 g CO2-e/MJ; or
if the energy source is wood or biomass, 4 g CO2-e/MJ.
In BV2.1, the symbol "g CO2-e/MJ" means "grams of Carbon Dioxide equivalent per megajoule/s".
BV2.2 Heated water storage temperature
Compliance with BP2.5 is verified for each heated water storage system when the water heater is designed such that all water is subjected to a temperature-dependent minimum exposure period as specified in Table BV2.2 within 7 days before passing through the water-heating appliance's heated water outlet.
Minimum exposure period
70°C or greater
B2.2 Water heater in a heated water supply system
In a new Class 1 or Class 10 building—
a water heater in a heated water supply system must be—
a solar water heater complying with B2.2(1)(b); or
a heat pump water heater complying with B2.2(1)(b); or
a gas water heater complying with B2.2(1)(c); or
an electric resistance water heater only in the circumstances described in B2.2(1)(d); or
a wood fired thermosiphon water heater or direct fired water heater each complying with AS/NZS 3500.4; and
a solar water heater and a heat pump water heater must have—
for a building with 1 or 2 bedrooms—
at least 14 Small-scale Technology Certificates for the zone where it is being installed; or
an energy saving of not less than 40% in accordance with AS/NZS 4234 for a "small" load system; and
for a building with 3 or 4 bedrooms—
at least 22 Small-scale Technology Certificates for the zone where it is being installed; or
an energy saving of not less than 60% in accordance with AS/NZS 4234 for a "medium" load system; and
for a building with more than 4 bedrooms
at least 28 Small-scale Technology Certificates for the zone where it is being installed; or
an energy saving of not less than 60% in accordance with AS/NZS 4234 for a "large" load system; and
In colder climates the performance of some heat pumps may diminish.
a gas water heater must be rated not less than 5 stars in accordance with AS 4552; and
an electric resistance water heater with no storage or a heated water delivery of not more than 50 litres in accordance with AS 1056.1 may be installed when—
the building has—
not more than 1 bedroom; and
not more than 1 electric resistance water heater installed; or
the greenhouse gas emission intensity of the public electricity supply is low.
B2.3 Layout of taps
B2.4 Maximum flow rates for heated water outlets
The outlet of a shower, basin, kitchen sink, or laundry trough must have a maximum flow rate of not more than 9 litres per minute.
The requirements of B2.4 do not apply to a shower intended to provide rapid drenching of a person for emergency purposes, such as chemical removal.
B2.5 Maximum delivery temperature
The delivery temperature of heated water at the outlet of each sanitary fixture must be—
not more than 45°C in any—
residential part of an aged care building; or
part of an early childhood centre, or primary or secondary school, that is used by children; or
B2.6 Temperature control devices
The required maximum delivery temperature must be achieved in accordance with AS/NZS 3500.4.
B2.7 Heated water storage
Containers used for producing and/or storing heated water must be provided with temperature and pressure relief devices in accordance with AS/NZS 3500.4.
B2.8 Legionella control
Legionella control for water heaters must be carried out in accordance with AS/NZS 3500.4.
B2.9 General requirements
Explanatory information: Cross-volume considerations
NCC Volume One Class 2 to 9 buildings
NCC Volume Two Class 1 and 10 buildings
Excavations for pipework adjacent to a building and footings
Termite management for attachments to buildings and penetrations through a slab
Penetrations for pipework through a vapour barrier
Pipework in timber bearers and joists of solid timber or engineered wood products
Fittings, fixtures and pipework installations in steel framed construction
Penetrations through a fire-resisting wall or floorC3 Protection of openings
Fixtures or fittings in a wet areaF1 Damp and weather proofing
Service pipework external to the building and penetrations through roof cladding in a bushfire prone area
Pipework sound insulation
Central heating pipework
Pool and spa heating and pumping – energy efficiency
Energy consumption monitoring for water heaters