Importance

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Abstract

A heat pump apparatus includes a start assist valve for permitting refrigerant to flow from an outlet of a condenser to an inlet of an evaporator during start-up of the heat pump apparatus. The heat pump apparatus preferably includes an expansion orifice connected in fluid communication between the outlet of the condenser and the inlet of the evaporator. The start assist valve provides a bypass for refrigerant flow around the expansion orifice during start-up of the heat pump apparatus. The apparatus also preferably includes a series of check valves cooperating with the start assist valve so that the start assist valve is operable only when the heat pump apparatus is in the cooling mode. The invention is particularly applicable to a direct expansion heat pump apparatus where one or more earth tap heat exchangers serve as the condenser when operating in the cooling mode. The apparatus preferably further includes a vapor refrigerant bleed connected in fluid communication with an expansion valve for bleeding vapor therefrom. The vapor bleeding causes the expansion valve to pass a greater amount of liquid refrigerant to thereby reduce liquid refrigerant in the condenser. Method aspects of the invention are also disclosed.

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First Claim