Control systems are provided that provide thermodynamically decoupled control of temperature and relative humidity and/or reduce or prevent frost formation or remove previously-formed frost. The control systems herein may be included as a component of a heating, ventilation, air conditioning, and refrigeration system that includes a heat exchanger.

Control systems are provided that provide thermodynamically decoupled control of temperature and relative humidity and/or reduce or prevent frost formation or remove previously-formed frost. The control systems herein may be included as a component of a heating, ventilation, air conditioning, and refrigeration system that includes a heat exchanger.

A ventilation and air-conditioning system includes: a heat-exchange ventilation apparatus discharging air in space to be ventilated drawn in from a first inlet to outdoors via a heat-exchange element, and blowing air in outdoors from a first outlet into the space to be ventilated via the heat-exchange element; and an air-conditioning apparatus including an indoor unit including a second inlet and a second outlet each installed in the space to be ventilated, and an outdoor unit installed outside the space to be ventilated, and drawing in air in the space to be ventilated from the second inlet and blowing the air from the second outlet into the space to be ventilated. The air-conditioning apparatus performs anti-freezing operation assist operation to blow air from the second outlet toward the first inlet, based on an anti-freezing operation assist request level indicating magnitude of risk of freezing occurring in the heat-exchange element.

A ventilation and air-conditioning system includes: a heat-exchange ventilation apparatus discharging air in space to be ventilated drawn in from a first inlet to outdoors via a heat-exchange element, and blowing air in outdoors from a first outlet into the space to be ventilated via the heat-exchange element; and an air-conditioning apparatus including an indoor unit including a second inlet and a second outlet each installed in the space to be ventilated, and an outdoor unit installed outside the space to be ventilated, and drawing in air in the space to be ventilated from the second inlet and blowing the air from the second outlet into the space to be ventilated. The air-conditioning apparatus performs anti-freezing operation assist operation to blow air from the second outlet toward the first inlet, based on an anti-freezing operation assist request level indicating magnitude of risk of freezing occurring in the heat-exchange element.

A heating, ventilation, and air conditioning (HVAC) system includes a closed loop refrigeration circuit including a heat exchanger assembly, a detection assembly operable to detect refrigerant from the closed loop refrigeration circuit mixed with air, a mitigation device operable to monitor at least one parameter associated with operation of the detection assembly and a controller operable to determine if an alarm generated by the detection assembly is a false alarm in response to the at least one parameter monitored by the mitigation device.

An air handler includes a housing with a heat exchanger core. The housing includes a faceplate, a roof panel, a base panel, a first side panel, and a second side panel. A first tunnel and a second tunnel are connected to the housing at the faceplate. A septum protrudes from the faceplate and connects the core at a front edge. The air handler further includes a first recirculation path and a second recirculation path inside the housing. The first and second recirculation paths are defined by the septum, the housing, and the core. The first and second recirculation paths are configured to direct a portion of airflow from the first tunnel to the second tunnel. The air handler further includes a first damper and a second damper disposed on the faceplate and configured to obstruct the first recirculation path and the second recirculation path respectively.

An air handler includes a housing with a heat exchanger core. The housing includes a faceplate, a roof panel, a base panel, a first side panel, and a second side panel. A first tunnel and a second tunnel are connected to the housing at the faceplate. A septum protrudes from the faceplate and connects the core at a front edge. The air handler further includes a first recirculation path and a second recirculation path inside the housing. The first and second recirculation paths are defined by the septum, the housing, and the core. The first and second recirculation paths are configured to direct a portion of airflow from the first tunnel to the second tunnel. The air handler further includes a first damper and a second damper disposed on the faceplate and configured to obstruct the first recirculation path and the second recirculation path respectively.

A control device controls a heating capacity during a heating operation and a defrosting capacity during a defrosting operation. The defrosting capacity of the first refrigeration cycle unit is determined to fall within a range satisfying a first determination condition and within a range satisfying a second determination condition. The first determination condition is a condition that a sum of a load capacity of a load device when the first defrosting start condition is satisfied, and the defrosting capacity of the first refrigeration cycle unit does not exceed the heating capacity of a second refrigeration cycle unit. The second determination condition is a condition that a sum of an inter-unit defrosting interval and a defrosting period of the first refrigeration cycle unit does not exceed a shortest defrosting interval of the second refrigeration cycle unit.

An air handler includes a housing with a heat exchanger core. The housing includes a faceplate, a roof panel, a base panel, a first side panel, and a second side panel. A first tunnel and a second tunnel are connected to the housing at the faceplate. A septum protrudes from the faceplate and connects the core at a front edge. The air handler further includes a first recirculation path and a second recirculation path inside the housing. The first and second recirculation paths are defined by the septum, the housing, and the core. The first and second recirculation paths are configured to direct a portion of airflow from the first tunnel to the second tunnel. The air handler further includes a first damper and a second damper disposed on the faceplate and configured to obstruct the first recirculation path and the second recirculation path respectively.

An air handler includes a housing with a heat exchanger core. The housing includes a faceplate, a roof panel, a base panel, a first side panel, and a second side panel. A first tunnel and a second tunnel are connected to the housing at the faceplate. A septum protrudes from the faceplate and connects the core at a front edge. The air handler further includes a first recirculation path and a second recirculation path inside the housing. The first and second recirculation paths are defined by the septum, the housing, and the core. The first and second recirculation paths are configured to direct a portion of airflow from the first tunnel to the second tunnel. The air handler further includes a first damper and a second damper disposed on the faceplate and configured to obstruct the first recirculation path and the second recirculation path respectively.