Assessment and improvement of a Control Verification Procedure in AHRI 210/240

In the U.S., AHRI 210/240 defines rating procedures for residential unitary equipment. However, the existing methodology fails to incentivize controller improvement as it relies on steady-state testing, requiring manufacturer-provided fixed-speed overrides that do not capture the influence of integrated controllers on unit performance. To partially address this deficiency, a Control Verification Procedure (CVP) was added to AHRI 210/240 to verify whether native operations align with the fixed-speed overrides. In this work, CVP testing revealed several issues that should be addressed, including unrepresentative thermostat placement, an unrealistic building load-line that can lead to degraded controller performance, humidity setpoints that triggered dehumidification operations, and a substantial test burden. Additionally, CVP includes an emulated thermostat (ET) provision for third-party stage-calling thermostats that was evaluated using two units, both of which exhibited compressor short-cycling due to a lack of sensor dynamics in the ET protocol. To eliminate this behavior, the ET formulation was modified to include 1st-order linear sensor dynamics emulating the filtering present within the thermostat. In response to the unrepresentative CVP load-line, the effects of the sensible load-line variation on test unit controller behavior and performance were evaluated. This work demonstrates that realistic load models are critical for evaluating controller behavior and system performance under load-based testing.