AS/NZS 5125.1:2014 outlines the method for determining the performance characteristics of air-source heat pump water heaters. It plays a critical role in the evaluation and compliance of heat pumps under Australia and New Zealand’s energy efficiency frameworks.
The results of AS/NZS 5125.1 testing feed directly into modelling conducted in accordance with AS/NZS 4234.
Performance Testing Approach
AS/NZS 5125.1 sets out standardised testing procedures and covers both stand-alone systems (where the heat pump is separate from the tank) and integral units (where the condenser wraps around the tank) under 700 L in size.
Key outputs from the AS/NZS 5125.1 test include:
- Thermal capacity — how much heat (kW) is delivered to the tank
- Power — how much power (kW) is used by the compressor and auxiliaries
- Coefficient of performance (COP) — the ratio of useful heat output to electrical input
Full heat-up cycles at different ambient air and water temperatures are performed in environmentally controlled chambers. A low-temperature performance test is also performed, used to characterise system performance in conditions where frost build-up on the evaporator is likely.
Link Between AS/NZS 5125.1 and AS/NZS 4234
The results from AS/NZS 5125.1 testing are used to train a regression model that estimates the unit’s COP and input power consumption. This feeds directly into the transient simulation models required by AS/NZS 4234.
The low-temperature performance test contributes to adjustments in efficiency within the model to account for frosting effects in cold conditions. Without AS/NZS 5125.1 testing, products under 700 L in size could not be modelled under the AS/NZS 4234 framework.
Design and Compliance Implications
Understanding AS/NZS 5125.1 is an important part of designing heat pump water heaters for the Australian market. Systems that perform poorly under these test conditions — especially during low-temperature testing or at temperatures relevant to rebate calculations — may:
- Receive low annual efficiency ratings
- Fail to meet minimum hot water delivery temperatures
- Qualify for reduced federal/state incentives
Manufacturers should consider compressor and evaporator sizing, control logic (set points, dead-bands), and tank aspect ratio when optimising for favourable AS/NZS 5125.1 results.
How EnergyAE Can Help
EnergyAE supports manufacturers and suppliers by connecting them with laboratories that carry out AS/NZS 5125.1 testing. We can assist with:
- R&D support — preparing models for testing and interpreting results
- AS/NZS 4234 modelling using 5125.1 test data
- End-to-end support from testing through to scheme registration
Contact us to discuss AS/NZS 5125.1 testing and modelling for your products.