AS/NZS 4234:2021
Heated water systems - Calculation of energy consumption
Standard sets out a method for evaluating the annual energy performance of water heaters using a combination of test results for component performance and mathematical models to determine the standardized annual supplementary energy use. Keywords: water heater; water heater energy evaluation; energy saving; energy performance; water heating technology; thermal collector; heat pump; photovoltaic array; thermal storage tank; solar water heater; heat pump water heater
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AS/NZS 4234:2021 Heated water systems - Calculation of energy consumption
Preface
Section 1 Scope and general
1.1 Scope
1.2 Application
1.3 Normative references
1.4 Terms and definitions
1.5 Notation
Section 2 Component testing
2.1 Scope of section
2.2 Water heater technology types
2.2.1 Solar thermal collector systems
2.2.2 Pump flow and power consumption
2.2.3 Air-source heat pump systems
2.2.4 Photovoltaic water heaters
2.3 Storage tank types
2.3.1 Electric resistive heated, unboosted and heat pump storage tanks
2.3.2 Gas-boosted storage vessels
2.4 In line water heater types
2.4.1 Instantaneous gas water heaters
2.4.2 In line instantaneous electric water heater
2.5 Solar-boosted heat pump storage water heaters
2.6 Solar collector
2.6.1 Collector efficiency
2.6.2 Incidence angle modifier
2.6.3 Collector efficiency correction for shadowing due to impact guard
2.7 Air source heat pump
2.7.1 Heat pump COP and electric power use
2.7.2 Additional tests for variable capacity compressors
2.7.3 Testing requirements for commercial heat pump water heaters
2.8 Domestic water heater configuration
Section 3 Performance evaluation of domestic water heaters
3.1 Performance evaluation simulation program
3.2 Weather data
3.3 Domestic thermal energy loads
3.4 Domestic electrical energy consumption
3.5 Domestic hot water load selection
3.5.1 Water heaters with grid electric or gas supplementary heating
3.5.2 Water heaters with heat pump supplementary heating
3.6 Water temperature
3.6.1 Control of temperature
3.6.2 Legionella control
3.6.3 Minimum delivery temperature
3.7 Cold water inlet temperature
Section 4 Modelling domestic water heaters
4.1 General
4.2 Thermal stratification and mixing in hot water storage tanks
4.2.1 General
4.2.2 Low-flow criteria
4.2.3 Controlled-flow pumped circulation
4.2.4 Uncontrolled-flow pumped circulation
4.2.5 External collector loop heat exchanger systems
4.2.6 Pump controllers
4.3 Modelling thermal stratification in storage tanks
4.3.1 General
4.3.2 Controlled flow-rate pumped circulation
4.3.3 Thermosiphon circulation
4.3.4 Uncontrolled flow-rate pumped circulation
4.3.5 Heat exchanger tanks
4.3.6 In-tank electric resistive heating from grid or PV power
4.4 Piping configuration for solar thermal water heaters
4.4.1 Collector loop piping
4.4.2 Collector loop piping insulation
4.4.3 Piping between primary storage tank and a series booster
4.5 Piping configuration for standalone heat pump
4.6 Energy consumed for freeze protection of solar and heat pump water heaters
4.6.1 Active pumped freeze protection
4.6.2 Electric heater freeze protection
4.7 Over-temperature control
4.7.1 General
4.7.2 Hot water discharge due to over-temperature
4.7.3 Vented system energy dumping
4.8 Modelling heat pump water heaters
4.8.1 Standard operating conditions
4.8.2 Standby electrical power
4.8.3 Water flow rate for standalone heat pumps
4.8.4 Low ambient temperature operation
4.8.5 Output for air temperature above lowest temperature test condition
4.8.6 Output for air temperature below lowest temperature test condition
4.9 Modelling gas storage water heaters
4.10 Modelling instantaneous gas water heaters
4.11 Modelling instantaneous electric water heaters
4.12 Modelling of PV water heaters
4.13 Modelling of indirect coupled PV water heaters
4.14 Modelling solar-boosted heat pump water heaters
4.14.1 General
4.14.2 Compressor performance
4.14.3 Solar-boosted evaporator
4.14.4 Heat gain from condensation
4.14.5 Heat pump condenser
4.14.6 Solution procedure
Section 5 Performance evaluation of commercial liquid heating systems
5.1 General
5.2 Standardized annual task performance
5.3 Weather data
5.4 Commercial thermal energy load
5.5 Liquid temperature
5.5.1 Legionella control for drinking water
5.5.2 Minimum delivery temperature for drinking water
5.5.3 Process heat systems
5.6 Cold water inlet temperature
5.6.1 Drinking water system
5.6.2 Open loop load system with partial recirculation
5.6.3 Closed loop load system
5.7 Reference water heaters for commercial systems
5.7.1 General
5.7.2 Electric-boosted products
5.7.3 Gas-boosted products
Section 6 Modelling commercial liquid heating systems (all types)
6.1 General
6.2 Solar collector array configuration
6.3 Storage tank heat loss
6.3.1 General
6.3.2 Tank standing heat loss calculation
6.4 Storage tank stratification for booster recirculation loop
6.5 Collector loop fluid flow rate
6.5.1 General
6.5.2 Hydraulic circuit analysis
6.5.3 Flow rate calculation procedure
Section 7 Test report
7.1 Product description
7.2 Simulation software features and validation
7.3 Calculation of annual energy savings relative to reference water heaters
7.4 Calculation of carbon dioxide equivalent emission from heated water systems (if required)
7.5 Presentation of results
7.6 Simulation files
Appendix A (normative) Standard domestic operating conditions for Australia
Appendix B (normative) Standard operating conditions for New Zealand
Appendix C (normative) Water heater parameters
Appendix D (normative) Corrections for effect of impact guards on solar collector efficiency
Appendix E (normative) Calculation of tank heat loss
Appendix F (Informative) Calculation of performance at other hot water loads
Bibliography
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References
Electric water heaters - Minimum Energy Performance Standard (MEPS) requirements and energy labelling
Installation and safety requirements for photovoltaic (PV) arrays
Thermal insulation - Housing and small buildings
Related Information
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AS/NZS 3598.1:2014
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AS/NZS 4234 Sup 1:2021
Heated water systems - Calculation of energy consumption-Parameters and outcomes for software simulations (Supplement to AS/NZS 4234:2021)
AS/NZS 4234:2021 Heated water systems - Calculation of energy consumption
Preface
Section 1 Scope and general
1.1 Scope
1.2 Application
1.3 Normative references
1.4 Terms and definitions
1.5 Notation
Section 2 Component testing
2.1 Scope of section
2.2 Water heater technology types
2.2.1 Solar thermal collector systems
2.2.2 Pump flow and power consumption
2.2.3 Air-source heat pump systems
2.2.4 Photovoltaic water heaters
2.3 Storage tank types
2.3.1 Electric resistive heated, unboosted and heat pump storage tanks
2.3.2 Gas-boosted storage vessels
2.4 In line water heater types
2.4.1 Instantaneous gas water heaters
2.4.2 In line instantaneous electric water heater
2.5 Solar-boosted heat pump storage water heaters
2.6 Solar collector
2.6.1 Collector efficiency
2.6.2 Incidence angle modifier
2.6.3 Collector efficiency correction for shadowing due to impact guard
2.7 Air source heat pump
2.7.1 Heat pump COP and electric power use
2.7.2 Additional tests for variable capacity compressors
2.7.3 Testing requirements for commercial heat pump water heaters
2.8 Domestic water heater configuration
Section 3 Performance evaluation of domestic water heaters
3.1 Performance evaluation simulation program
3.2 Weather data
3.3 Domestic thermal energy loads
3.4 Domestic electrical energy consumption
3.5 Domestic hot water load selection
3.5.1 Water heaters with grid electric or gas supplementary heating
3.5.2 Water heaters with heat pump supplementary heating
3.6 Water temperature
3.6.1 Control of temperature
3.6.2 Legionella control
3.6.3 Minimum delivery temperature
3.7 Cold water inlet temperature
Section 4 Modelling domestic water heaters
4.1 General
4.2 Thermal stratification and mixing in hot water storage tanks
4.2.1 General
4.2.2 Low-flow criteria
4.2.3 Controlled-flow pumped circulation
4.2.4 Uncontrolled-flow pumped circulation
4.2.5 External collector loop heat exchanger systems
4.2.6 Pump controllers
4.3 Modelling thermal stratification in storage tanks
4.3.1 General
4.3.2 Controlled flow-rate pumped circulation
4.3.3 Thermosiphon circulation
4.3.4 Uncontrolled flow-rate pumped circulation
4.3.5 Heat exchanger tanks
4.3.6 In-tank electric resistive heating from grid or PV power
4.4 Piping configuration for solar thermal water heaters
4.4.1 Collector loop piping
4.4.2 Collector loop piping insulation
4.4.3 Piping between primary storage tank and a series booster
4.5 Piping configuration for standalone heat pump
4.6 Energy consumed for freeze protection of solar and heat pump water heaters
4.6.1 Active pumped freeze protection
4.6.2 Electric heater freeze protection
4.7 Over-temperature control
4.7.1 General
4.7.2 Hot water discharge due to over-temperature
4.7.3 Vented system energy dumping
4.8 Modelling heat pump water heaters
4.8.1 Standard operating conditions
4.8.2 Standby electrical power
4.8.3 Water flow rate for standalone heat pumps
4.8.4 Low ambient temperature operation
4.8.5 Output for air temperature above lowest temperature test condition
4.8.6 Output for air temperature below lowest temperature test condition
4.9 Modelling gas storage water heaters
4.10 Modelling instantaneous gas water heaters
4.11 Modelling instantaneous electric water heaters
4.12 Modelling of PV water heaters
4.13 Modelling of indirect coupled PV water heaters
4.14 Modelling solar-boosted heat pump water heaters
4.14.1 General
4.14.2 Compressor performance
4.14.3 Solar-boosted evaporator
4.14.4 Heat gain from condensation
4.14.5 Heat pump condenser
4.14.6 Solution procedure
Section 5 Performance evaluation of commercial liquid heating systems
5.1 General
5.2 Standardized annual task performance
5.3 Weather data
5.4 Commercial thermal energy load
5.5 Liquid temperature
5.5.1 Legionella control for drinking water
5.5.2 Minimum delivery temperature for drinking water
5.5.3 Process heat systems
5.6 Cold water inlet temperature
5.6.1 Drinking water system
5.6.2 Open loop load system with partial recirculation
5.6.3 Closed loop load system
5.7 Reference water heaters for commercial systems
5.7.1 General
5.7.2 Electric-boosted products
5.7.3 Gas-boosted products
Section 6 Modelling commercial liquid heating systems (all types)
6.1 General
6.2 Solar collector array configuration
6.3 Storage tank heat loss
6.3.1 General
6.3.2 Tank standing heat loss calculation
6.4 Storage tank stratification for booster recirculation loop
6.5 Collector loop fluid flow rate
6.5.1 General
6.5.2 Hydraulic circuit analysis
6.5.3 Flow rate calculation procedure
Section 7 Test report
7.1 Product description
7.2 Simulation software features and validation
7.3 Calculation of annual energy savings relative to reference water heaters
7.4 Calculation of carbon dioxide equivalent emission from heated water systems (if required)
7.5 Presentation of results
7.6 Simulation files
Appendix A (normative) Standard domestic operating conditions for Australia
Appendix B (normative) Standard operating conditions for New Zealand
Appendix C (normative) Water heater parameters
Appendix D (normative) Corrections for effect of impact guards on solar collector efficiency
Appendix E (normative) Calculation of tank heat loss
Appendix F (Informative) Calculation of performance at other hot water loads
Bibliography
Previous versions
AS/NZS 4234:2021
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.