Blocked fan detection system for heat pump
First Claim
1. An airflow obstruction detection method for detecting an airflow obstruction condition in an outdoor heat exchanger, comprising the steps of:
- determining a temperature difference parameter indicative of temperature difference between the outdoor heat exchanger and the ambient air surrounding said heat exchanger at a first time;
performing a defrost cycle when the temperature difference parameter exceeds a predetermined value;
determining the temperature difference parameter at a second time after defrost cycle has completed;
declaring an obstruction condition to exist if the temperature difference parameter determined at said second time is not smaller by a predetermined value than the temperature difference determined at said first time.
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Accused Products
Abstract
The blocked fan or obstructed airflow condition is detected by measuring the difference between outdoor air temperature and outdoor exchanger coil temperature. If a very high difference is detected, or if no decrease in the difference is achieved after termination of the defrost cycle, and if either of these conditions persists over a plurality of defrost cycles, then the blocked condition is declared. The diagnostic system can be integrated in an existing demand defrost cycle and is capable of detecting blocked conditions attributable to foreign matter such as leaves, paper and debris which cannot be cleared by defrosting.
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Citations
12 Claims
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1. An airflow obstruction detection method for detecting an airflow obstruction condition in an outdoor heat exchanger, comprising the steps of:
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determining a temperature difference parameter indicative of temperature difference between the outdoor heat exchanger and the ambient air surrounding said heat exchanger at a first time; performing a defrost cycle when the temperature difference parameter exceeds a predetermined value; determining the temperature difference parameter at a second time after defrost cycle has completed; declaring an obstruction condition to exist if the temperature difference parameter determined at said second time is not smaller by a predetermined value than the temperature difference determined at said first time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification