| 摘要 |
A heat pump having successive defrosting operations initiated, controlled and timed by a microprocessor-based controller. The time intervals between defrost cycles are periodically varied as needed, dependent on outdoor temperature and certain operating conditions of the heat pump system. Initially the microprocessor is programmed to select and establish a minimum outdoor temperature-related defrost lockout time interval which may then be automatically extended during the lockout period by amounts of time during which, simultaneously, the outdoor coil is above a predetermined coil temperature level and the heat pump compressor is not running. The minimum defrost lockout interval is periodically revised and established, within certain limits, at a value which is dependent on outdoor temperature. An optional feature allows different time vs. temperature lockout time interval functions to be established for different geographical areas having marked differences in average cold weather climatic conditions.
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