Lessons Learned from Load-Based Testing of Heat Pumps
How is performance of variable-speed heat pumps accurately measured? NEEA collaborated with PG&E, BC Hydro, and Purdue University to find out.
Using CSA EXP07:19, a load-based test and rating procedure for residential air-source heat pumps and air conditioners, the collaboration determined that load-based testing offers a better way to measure the complex performance of modern, variable-speed systems.
Testing revealed complex equipment behavior that is often built into product firmware but not revealed in conventional lab test procedures, uncovering substantial performance variability and substantial differences in relative ranking of products.
The single largest reason for the performance variability is a result of the equipment’s built-in controls. Load based testing reveals products that have unstable built-in logic control.
Why do these results matter? Load-based testing:
- Offers performance ratings that more closely represent real-world performance
- Reduces uncertainty in program evaluations
- Improves the quality of information available for customer and contractor product choices
- Increases the savings potential of efficiency programs
The most significant conclusions of the research are as follows:
- Load-based testing can provide more information about relative efficiencies of various models, generally and for specific climates, compared with the current AHRI 210/240 test and rating results.
- The single largest reason for the performance variability is a result of the equipment’s built-in controls. Load-based testing reveals products that have unstable built-in logic control.
- The future version of EXP07 (SPE07) is designed to reduce uncertainty and improve test-to-test repeatability and lab-to-lab reproducibility.
- A load-based test can increase transparency in the testing and rating process and provide improved differentiation among products to help regional markets select the best products for their applications.
