Abstract: A method of controlling an orifice of a valve in an HVAC system to regulate a flow of a primary fluid through a primary side of a thermal energy exchanger of the HVAC system and thereby adjust a thermal energy transfer by the thermal energy exchanger from the primary fluid to a secondary fluid, flowing through a secondary side of the thermal energy exchanger, includes adjusting, by one or more electronic circuits, the orifice of the valve by applying an efficiency control algorithm to a control setpoint for the valve, the efficiency control algorithm processing the control setpoint for the valve to maintain energy-efficient thermal energy transfer. The method further includes the one or more electronic circuits determining the control setpoint for the valve, using current performance values of the HVAC system and recorded historical data of the HVAC system.

Abstract: A method for determining antifreeze content in a fluid of a heating, ventilation, and air conditioning (HVAC) system includes receiving, in a processor, measurement data of the fluid, the measurement data comprising a measured temperature of the fluid and a measured speed of sound in the fluid, calculating, in the processor, for each of a plurality of antifreeze concentration values a fitting parameter, using the measurement data and one or more of previous measurement data or previous antifreeze concentration data, and determining, in the processor, an antifreeze concentration in the fluid by selecting the antifreeze concentration value with an optimal fitting parameter.

Abstract: For balancing a hydronic network that comprises a plurality of parallel zones with a regulating valve in each zone, individual flow characteristics are determined (S1) for each of the regulating valves, by recording the total flow of fluid measured at different valve positions of a respective regulating valve, while the remaining other regulating valves are set to a closed valve position. Dependent flow characteristics are determined (S2) by recording the total flow of fluid measured at different valve positions of the respective regulating valve, while the remaining other regulating valves are set to an open valve position. Correction factors are determined (S3) for each of the regulating valves, using the individual flow characteristics and the dependent flow characteristics. The hydronic network is balanced (S4) by setting the valve positions of the regulating valves using target flows and the correction factors.