Abstract: A heat exchanger assembly including a heat exchanger that has a first end and a second end opposite the first end, and a cover coupled to the second end. The heat exchanger also includes a plurality of fins with a first fin disposed adjacent the first end and a second fin disposed adjacent the second end, and a continuous, serpentine coil. The coil includes first return bends projecting beyond the first fin and second return bends projecting beyond the second fin. The cover has a base plate and separate receptacles encasing one or more of the second return bends to permit airflow through the encased second return bends. The base plate is positioned on the second end to inhibit airflow from one of the receptacles to another of the receptacles.

Abstract: A heat exchanger assembly including a heat exchanger that has a first end and a second end opposite the first end, and a cover coupled to the second end. The heat exchanger also includes a plurality of fins with a first fin disposed adjacent the first end and a second fin disposed adjacent the second end, and a continuous, serpentine coil. The coil includes first return bends projecting beyond the first fin and second return bends projecting beyond the second fin. The cover has a base plate and separate receptacles encasing one or more of the second return bends to permit airflow through the encased second return bends.

Abstract: Heat pumps with improved defrost cycles and methods of defrosting heat exchangers, for example, having microchannel outdoor heat exchangers. A heat exchanger has three types of connection points that are used during a defrost cycle. Two connection points are used to deliver hot refrigerant gas to the heat exchanger and one connection point is where refrigerant exits the heat exchanger. Two of the connection points are at the same header and during at least part of the defrost cycle, at least part of the hot refrigerant gas is passed through that header without passing through any cross tubes of the heat exchanger. A defrost valve in a refrigerant conduit opens during the defrost cycle to deliver hot refrigerant gas to the connection point on the header. In a number of embodiments, the defrost valve is open only during a portion of the defrost cycle.

Abstract: Heat pumps with improved defrost cycles and methods of defrosting heat exchangers, for example, having microchannel outdoor heat exchangers. A heat exchanger has three types of connection points that are used during a defrost cycle. Two connection points are used to deliver hot refrigerant gas to the heat exchanger and one connection point is where refrigerant exits the heat exchanger. Two of the connection points are at the same header and during at least part of the defrost cycle, at least part of the hot refrigerant gas is passed through that header without passing through any cross tubes of the heat exchanger. A defrost valve in a refrigerant conduit opens during the defrost cycle to deliver hot refrigerant gas to the connection point on the header. In a number of embodiments, the defrost valve is open only during a portion of the defrost cycle.

Abstract: Heat pumps with improved defrost cycles and methods of defrosting heat exchangers, for example, having microchannel outdoor heat exchangers. A heat exchanger has three types of connection points that are used during a defrost cycle. Two connection points are used to deliver hot refrigerant gas to the heat exchanger and one connection point is where refrigerant exits the heat exchanger. Two of the connection points are at the same header and during at least part of the defrost cycle, at least part of the hot refrigerant gas is passed through that header without passing through any cross tubes of the heat exchanger. A defrost valve in a refrigerant conduit opens during the defrost cycle to deliver hot refrigerant gas to the connection point on the header. In a number of embodiments, the defrost valve is open only during a portion of the defrost cycle.