Heating and cooling systems using differential pressure (DP) meters, orifice plates, or V-Cones need more than just a flow reading to calculate real energy use. You need density, enthalpy, and a few other thermodynamic properties, worked out correctly for the actual fluid temperature. That is what the Contrec 515 HC04 Heat Calculator does.
It reads a single or stacked DP input from the flow element, using the ISO 5167 or V-Cone equations, and combines this with feed and return temperature readings. From actual application, this matters because DP flow calculations shift with fluid density and viscosity, which themselves change with temperature, so getting this right needs to happen inside the instrument, not as a separate manual correction.
The calculations are based on the IAPWS Industrial Formulation (1997), the same reference used for accurate steam and water thermodynamic properties. Temperature readings are used to work out fluid density and specific enthalpy, and the instrument also calculates the isentropic exponent and absolute viscosity needed for the DP flow equations themselves.
Before we quote this, we would normally check your DP transmitter or flow element type, the feed/return temperature range, and whether you need a single or stacked DP configuration.
Hope this helps.
