Patent ID: 7004246

Claim:
A heat pump being reversible between a heating cycle and a cooling cycle, comprising: a compressor; an indoor coil; an outdoor coil; an expansion means between the indoor coil and the outdoor coil, the expansion means being in fluid communication with the indoor coil and the outdoor coil for allowing flow of the refrigerant fluid between the indoor coil and the outdoor coil; a sensor for detecting a condition of the outdoor coil and providing a signal indicative of the condition of the outdoor coil; a controller including a predetermined set point and means for receiving the signal indicative of the condition of the outdoor coil, the controller being configured to provide at least one signal when the predetermined set point has been achieved, the predetermined set point of the controller corresponding to a first temperature, and the controller being configured to provide at least one signal in response to a determination that the first temperature has been achieved in the outdoor coil; and a refrigerant bypass circuit to provide refrigerant to the outdoor coil at an elevated temperature, the refrigerant bypassing the expansion means, the bypass circuit comprising a valve operable between a first closed position and a second open position in response to the at least one signal from the controller, the at least one signal from the controller causing the valve in the bypass circuit to open, thereby permitting flow of hot refrigerant gas through the bypass circuit to the outdoor coil to defrost the coil, a timing means for determining closing of the valve in the bypass circuit after expiration of a preselected period of time after activation, the timing means further including an additional means of sending a signal at the expiration of the preselected period to cause the valve in the bypass circuit to close, a refrigerant fluid supply means, the supply means providing refrigerant fluid to the valve from between the compressor and the expansion device, a refrigerant fluid discharge means providing refrigerant discharge fluid passing through the valve to the outdoor coil, the refrigerant from the refrigerant bypass circuit at an elevated temperature defrosting the outdoor coil when the bypass circuit valve is open.