Heat reclamation from and adjustment of defrost cycle

A method of adjusting the length of time of a next subsequent defrost cycle of removing accumulated frost from an outdoor heat exchanger coil including an outdoor fan forming a portion of a refrigerant heat pump system comprising the steps of:

• initiating a defrost cycle upon comparing the comparison between outdoor ambient temperature and outdoor heat exchanger coil refrigerant temperature with a defrost initiation reference level, wherein the defrost initiation reference level is calculated by solving the temperature equation:
• T.sub.c =4/5 T.sub.o +Y, where T.sub.c is the outdoor heat exchanger coil refrigerant temperature, T.sub.o is the outdoor ambient temperature and Y is an ordinate intercept of the outdoor heat exchanger coil refrigerant temperature;
• terminating the defrost cycle;
• determining the length of time of the defrost cycle;
• adjusting the defrost initiation reference level for the initiation of the next subsequent defrost cycle when said defrost cycle is outside a predetermined time period, wherein the adjustment of the defrost initiation reference level includes adjusting the ordinate intercept (Y) upwardly by 1.5.degree. C. when said length of time of the defrost cycle is greater than nine minutes and adjusting the ordinate intercept downwardly by 0.5.degree. C. when said length of time of the defrost cycle is less than or equal to five minutes;
• and
• operating a heat reclaim cycle with the outdoor fan deenergized until the outdoor heat exchanger coil refrigerant temperature is less than or equal to 5.5.degree. C.