Abstract: An energy recovery ventilator includes first and second blowers, a pressure transducer and a controller. The first blower is configured to direct a first air stream into a first zone of an enclosure. A second blower configured to direct a second air stream into a second zone of the enclosure. A pressure transducer is configured to determine internal air pressure within the enclosure. A controller is configured to control the first blower and/or the second blower in response to the internal air pressure.

Abstract: One aspect, as provided herein, is directed to a multi-stage fluid control system for a fluid source heat pump system. This embodiment comprises compressors configured to operate as separate, heat exchange stages, condensers each being fluidly coupled to at least one of the compressors by refrigerant tubing and having intake ends coupled together by a fluid intake manifold. This embodiment further includes output conduits coupled to each of the condensers and that are couplable to a distal location. Further included is a modulating valve control system interposed the output conduits. The modulating valve control system is configured to stage a flow of fluid through the condensers based on a number of operating compressors.

Abstract: A tubular heat exchanger has at least one pair of dimples which are extruded into at least one tube of the heat exchanger by deforming the tube wall inwardly. The dimples of each pair are in generally facing relationship, but are offset with respect to each other along a longitudinal axis of the tube, which slows down the flow of flue gas in the tube when the heat exchanger is in operation and increases the turbulence of the gas, thereby enhancing the transfer of heat from the flue gas to air flowing across the outer surfaces of the heat exchanger. The offset design allows each dimple to protrude beyond the centerline of the tube, which alters the direction of the flue gas flowing in the tube.