A dual reclaim coil with a smart control application is provided that allows the refrigerant inlet to the HVAC unit switch between the two sides of the condenser is aimed to use the high temperature and pressure of the condenser/gas cooler outlet while a CO.sub.2 refrigerant system is operating above critical point. This occurs in hot ambient conditions, when the need for heating in the space is not as great as in the wintertime and the available heat at the condenser/gas cooler's outlet is sufficient to satisfy the heating load. This also mitigates space overcooling, while increasing the CO.sub.2 transcritical system's efficiency by subcooling the refrigerant for applications involving dehumidification HVAC systems which often results in a phenomenon called “overcooling” during the dehumidification season.

The present disclosure relates to a heating, ventilation, and air conditioning (“HVAC”) system include a supply damper, a return damper, and a defrost damper which are operable to control a supply airflow, a return airflow, and a defrost airflow to flow between a supply duct, a return duct, and an indoor heat exchanger without substantially flowing into and substantially cooling an indoor space. A reheat coil may also warm the supply air flow and a defrost return line may be used to bypass a bi-flow expansion device and an indoor heat exchanger.

Provided are a refrigeration heat reclaim unit and method, comprising a heat exchanger, comprising a refrigerant inlet that receives a flow of refrigerant having a first state; a refrigerant outlet that outputs the flow of refrigerant having a second state; a water loop inlet that receives a flow of liquid at a first temperature; a water loop outlet that outputs the flow of liquid from the reclaim heat exchanger at a second temperature that is greater than the first temperature in response to the flow of refrigerant. The refrigeration reclaim unit also comprises a refrigerant flow control device having outputs to the refrigerant inlet and an air-cooled condenser, respectively for controlling the flow of refrigerant to at least one of the refrigerant inlet and the air-cooled condenser for maintaining a predetermined flow quality value at the refrigerant outlet.

Provided are a refrigeration heat reclaim unit and method, comprising a heat exchanger, comprising a refrigerant inlet that receives a flow of refrigerant having a first state; a refrigerant outlet that outputs the flow of refrigerant having a second state; a water loop inlet that receives a flow of liquid at a first temperature; a water loop outlet that outputs the flow of liquid from the reclaim heat exchanger at a second temperature that is greater than the first temperature in response to the flow of refrigerant. The refrigeration reclaim unit also comprises a refrigerant flow control device having outputs to the refrigerant inlet and an air-cooled condenser, respectively for controlling the flow of refrigerant to at least one of the refrigerant inlet and the air-cooled condenser for maintaining a predetermined flow quality value at the refrigerant outlet.

A monitoring system is disclosed for a heating, ventilation, or air conditioning (HVAC) system of a residential or commercial building. The monitoring system includes an evaporator unit device including a first current sensor that measures current supplied to a circulator blower. The measured current from the first current sensor is used to diagnose a problem with the circulator blower. The monitoring system includes a first temperature sensor that measures refrigerant temperature between a condenser and an expansion valve. The monitoring system includes a second temperature sensor that measures refrigerant temperature between an evaporator and a compressor. The monitoring system includes a condenser unit device that communicates with the evaporator unit device. The condenser unit device includes a second current sensor that measures current supplied to the compressor. The evaporator unit device transmits sensor data to a remote monitoring service over a data network.

A monitoring system for a heating, ventilation, or air conditioning (HVAC) system of a residential or commercial building includes an evaporator unit device and four temperature sensors. The evaporator unit device includes an electrical sensor that measures current supplied to a circulator blower of the HVAC system. The measured current from the first electrical sensor is used to diagnose a problem with the circulator blower. The first temperature sensor that measures a temperature of refrigerant flowing between a condenser of the HVAC system and an expansion valve of the HVAC system. The second temperature sensor measures a temperature of refrigerant flowing between an evaporator and a compressor. The third temperature sensor measures a temperature of air flowing away from the evaporator. The fourth temperature sensor measures a temperature of air flowing toward the evaporator. The evaporator unit device transmits sensor data to a remote monitoring service over a data network.

The present disclosure relates to a heating, ventilation, and air conditioning (HVAC) system include a supply damper, a return damper, and a defrost damper which are operable to control a supply airflow, a return airflow, and a defrost airflow to flow between a supply duct, a return duct, and an indoor heat exchanger without substantially flowing into and substantially cooling an indoor space. A reheat coil may also warm the supply air flow and a defrost return line may be used to bypass a bi-flow expansion device and an indoor heat exchanger.

A dual reclaim coil with a smart control application is provided that allows the refrigerant inlet to the HVAC unit switch between the two sides of the condenser is aimed to use the high temperature and pressure of the condenser/gas cooler outlet while a CO.sub.2 refrigerant system is operating above critical point. This occurs in hot ambient conditions, when the need for heating in the space is not as great as in the wintertime and the available heat at the condenser/gas cooler's outlet is sufficient to satisfy the heating load. This also mitigates space overcooling, while increasing the CO.sub.2 transcritical system's efficiency by subcooling the refrigerant for applications involving dehumidification HVAC systems which often results in a phenomenon called overcooling during the dehumidification season.

A system for refrigerant leakage detection includes one or more sensors configured to detect one or more parameters of a building system including a refrigerant. The system further includes one or more storage devices storing instructions thereon that, when executed by one or more processors, cause the one or more processors to receive sensor data from the one or more sensors; apply the sensor data to a long short-term memory (LSTM) model to generate predicted sensor data corresponding to the one or more sensors; receive subsequent sensor data from the one or more sensors; compare the predicted sensor data to the subsequent sensor data; determine that the building system has a refrigerant leakage based on the comparison of the predicted sensor data to the subsequent sensor data; and, responsive to determining that the building system has the refrigerant leakage, take an action to address the refrigerant leakage.

The present disclosure relates to a heating, ventilation, and air conditioning (HVAC) system include a supply damper, a return damper, and a defrost damper which are operable to control a supply airflow, a return airflow, and a defrost airflow to flow between a supply duct, a return duct, and an indoor heat exchanger without substantially flowing into and substantially cooling an indoor space. A reheat coil may also warm the supply air flow and a defrost return line may be used to bypass a bi-flow expansion device and an indoor heat exchanger.