Standard
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AS/NZS 4234:2008
[Available Superseded]Heated water systems - Calculation of energy consumption
Sets out a method of evaluating the annual energy performance of water heaters using a combination of test results for component performance and a mathematical model to determine the standardized annual purchased energy use. The procedure is applicable to electric, gas and solar water heaters with integral boosting or preheating into a conventional storage or instantaneous water heater and to heat pump water heaters. For solar and heat pump water heaters, displaced purchased energy relative to reference water heaters is also calculated.
Published: 21/08/2008
Pages: 73
Table of contents
Cited references
Content history
Table of contents
Header
About this publication
Preface
1 Scope and general
1.1 Scope
1.2 Application
1.3 Referenced documents
1.4 Definitions
1.5 Notation
2 Input parameters
2.1 Introduction
2.2 Component testing
2.2.1 Electric boosted, un-boosted and heat pump storage tanks
2.2.2 Gas boosted storage vessels
2.2.3 Instantaneous gas water heaters
2.2.4 Solar boosted heat pump storage water heaters
2.2.5 Flow rate in pumped collector-loops
2.2.5.1 Constant speed pumps
2.2.5.2 Variable speed pumps
2.2.6 Solar collector efficiency
2.2.7 Incidence angle modifier
2.2.7.1 General
2.2.7.2 Flat plate collectors
2.2.7.3 Evacuated tubular collectors
2.3 Collector efficiency correction for shadowing due to impact guard
2.4 Water heater configuration
3 Performance evaluation
3.1 Standardized annual task performance
3.2 Weather data
3.3 Thermal energy loads
3.4 Minimum solar performance
3.5 Water temperature
3.5.1 Control of temperature
3.5.2 Minimum delivery temperature
3.6 Cold water inlet temperature
3.7 Pumped circulation control in solar water heaters
3.7.1 General
3.7.2 Low-flow criteria
3.7.3 Controlled-flow pumped-circulation
3.7.4 Uncontrolled-flow pumped circulation
3.7.5 External collector loop heat exchanger systems
3.7.6 Pump controllers
3.8 TRNSYS deck setup for modelling thermal stratification in solar heated storage tanks
3.8.1 General
3.8.2 Controlled flow-rate pumped circulation
3.8.3 Thermosiphon circulation
3.8.4 Uncontrolled flow-rate pumped circulation
3.8.5 Heat exchanger tanks
3.9 Piping configuration for solar water heaters
3.9.1 Collector loop piping
3.9.2 Collector loop piping insulation
3.9.3 Piping between primary storage tank and a series booster
3.9.3.1 Pumped system
3.9.3.2 Thermosiphon system
3.10 Energy consumed for freeze protection of solar water heaters
3.10.1 Active pumped freeze protection
3.10.2 Electric heater freeze protection
3.11 Over-temperature control
3.11.1 General
3.11.2 Hot water discharge due to over temperature
3.11.3 Vented system energy dumping
3.12 Modelling gas storage water heaters
3.13 Modelling instantaneous gas water heaters
3.14 Presentation of results
3.14.1 Purchased energy savings relative to reference water heaters
3.14.2 Calculation to determine specific carbon dioxide equivalent emission from heated water systems
3.14.3 Documentation of simulation model inputs and outputs
Appendix A
A1 Scope
A2 Time-limited electric supply
A3 Solar collector inclination and orientation
A4 Climate data
A5 Hot water thermal energy loads
A5.1 Daily thermal load
A5.2 Hourly loads
A5.3 Seasonal load profile
A6 Cold water inlet temperature
A7 Characteristics of reference water heaters in zones 1 to 4
A8 Purchased energy of reference water heaters in zones 1 to 4
A9 Displaced energy
A9.1 Electric boosted products
A9.2 Gas boosted products
Appendix B
B1 Scope
B2 Time-limited electric supply
B3 Solar collector inclination and orientation
B4 Climate data
B5 Hot water thermal energy loads
B5.1 Daily thermal load
B5.2 Daily load profile
B5.3 Seasonal load profile
B5.4 Hourly load
B6 Cold water inlet temperature
B7 Characteristics of reference water heaters in zones 5 and 6
B8 Purchased energy for reference water heaters in zones 5 to 6
B9 Displaced energy
B9.1 Electric boosted products
B9.2 Gas boosted products
Appendix C
C1 General
C2 Thermosiphon solar water heaters
C3 Pumped circulation solar water heater
C4 Supplementary boosting
C5 Controlled flow rate systems
C6 Collector loop heat exchanger (if used)
C7 Plumbing between solar tank and solar collector
C8 Load flow heat exchanger (if used)
C9 Solar boosted heat pump water heater
C10 Supplementary boosting
C11 Solar boosted evaporator
C12 Condenser—Wrap‑Around
C13 Heat pump compressor
Appendix D
D1 General
D2 Normal incidence shadowing
D2.1 Cylindrical mesh guard
D2.2 Flat cover guard
D3 Incidence angle modifier correction
D3.1 General
D3.2 Cylindrical mesh guard—Incidence angle modifier
D3.3 Flat sheet cover guard incidence angle modifier
Appendix E
E1 General
E2 TRNSYS deck examples
E3 Source code
E4 Non-linear solar collector efficiency characterization
E5 Incidence angle modifier
E5.1 General
E5.2 Symmetric collectors
E5.3 Data table of incidence angle modifier values
E5.4 Collectors with north–south and east–west symmetry
E5.5 Incidence angle modifier map
E5.6 Collectors with east–west symmetry only
E6 Collector configuration
E6.1 General
E6.2 Collector heat removal via heat pipe
E6.3 Thermosiphon systems with collector loop heat exchanger
E6.4 Serpentine riser solar collector
E6.5 Thermal cut-off valve in the thermosiphon loop
E7 Storage tank configuration
E7.1 Over-temperature relief valve
E7.2 One-shot boosting
E8 Bibliography
Appendix F
Appendix G
Appendix H
H1 General requirements and definitions
H1.1 General requirements
H1.2 Definitions
H1.2.1 Integral heat pump
H1.2.2 Low temperature operation penalty
H1.2.3 Stand-alone heat pump
H1.2.4 Thermal capacity
H2 Input parameters
H2.1 Heat pump COP and electric power use
H2.2 Water flow rate for stand-alone heat pumps
H2.2.1 Systems with constant speed water pumps
H2.2.2 Systems with water flow rate control
H2.3 Heat pump operation penalty at low temperatures
H3 Pumped circulation control in heat pump water heaters
H3.1 General
H3.2 Low-flow criteria for heat pumps
H3.3 Controlled-flow pumped-circulation
H3.4 Uncontrolled-flow pumped circulation
H3.5 External heat exchanger systems
H4 TRNSYS deck setup for modelling thermal stratification in storage tanks
H4.1 General
H4.2 Controlled flow-rate pumped circulation
H4.3 Thermosiphon sidearm circulation
H4.4 Uncontrolled flow-rate pumped circulation
H5 Piping configuration
H5.1 Stand-alone heat pump water heaters—Loop piping
H5.2 Stand-alone heat pump water heaters—Piping insulation
H5.3 Piping between primary storage tank and a series booster
H6 Standby electrical power
H7 Low ambient temperature operation
H7.1 Systems not suitable for low temperature operation
H7.2 Systems suitable for operation at low ambient temperatures
H8 Modelling heat output
H8.1 Output for air temperature above lowest temperature test condition
H8.1.1 Integral heat pumps
H8.1.2 Stand-alone heat pumps
H8.2 Output for air temperature below lowest temperature test condition
H8.2.1 Low temperature Class B products
H8.2.2 Low temperature Class A products
H8.2.2.1 Low temperature operation penalty calculation
H8.2.2.2 Calculation
H9 Standard operating conditions for air-source heat pump water heaters in Australia
H9.1 General
H9.2 Climate data
H9.3 Hot water thermal energy loads
H9.4 Characteristics of reference water heaters for zones HP1-Au to HP5-Au
H9.5 Purchased energy for reference water heaters in zones HP1-Au to HP5-Au
H9.6 Displaced energy
H10 Standard operating conditions for air-source heat pump water heaters in New Zealand
H10.1 General
H10.2 Climate data
H10.3 Hot water thermal energy loads
H10.4 Characteristics of reference water heaters in zones HP1-NZ and HP2-NZ
H10.5 Purchased energy for reference water heaters in zones HP1-NZ and HP2-NZ
H10.6 Displaced energy
H11 Air-source heat pump water heater parameters
Appendix I
Amendment control sheet
Cited references in this standard
[Current]
Electric water heaters, Part 2: Minimum Energy Performance Standard (MEPS) requirements and energy labelling
[Current]
Heat pump water heaters — Performance assessment, Part 1: Air source heat pump water heaters
[Current]
Safety and public health requirements for plumbing products — Water heaters and hot-water storage tanks
[Current]
Electric water heaters, Part 1: Energy consumption, performance and general requirements
Content history
[Current]
[Superseded]
[Superseded]
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[Available Superseded]
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