DETECTION OF EFFICIENCY DEGRADATION IN HVAC&R SYSTEMS

An HVAC&R monitor detects short-term and long-term system efficiency degradations by modeling either compressor input power or current. The model is continuously updated with new or recent temperature and power parameter measurements reflecting the most up-to-date operating condition of the system. Short-term system degradations are detected instantaneously by comparing compressor power or current as predicted by the model against measured power or current usage. Long-term system degradations are detected over time by monitoring the sensitivity of the compressor power or current usage to evaporator and/or condenser fluid temperatures. An appropriate warning and/or signal may be issued if system efficiency degradation is detected.