Patent ID: 8805591

Claim:
An energy consumption monitoring system for a fluid-based heating or cooling system with a fluid flow therethrough, comprising: a heating or cooling device; a supply line connected to the heating or cooling device, the supply line carrying fluid to the heating or cooling device at a first temperature; a return line connected to the heating or cooling device, the return line carrying fluid from the heating or cooling device at a second temperature different than the first temperature; a first temperature sensor coupled to the supply line and positioned to measure the first temperature; a second temperature sensor coupled to the return line and positioned to measure the second temperature, wherein a temperature difference between the first and second temperatures is a temperature change across the heating or cooling device; a pressure independent, constant-flow control valve assembly comprising a valve body with an inlet and an outlet, a valve chamber therein, a fluid path extending between the inlet, outlet and the valve chamber; an adjustable valve member in the valve chamber and disposed in the fluid path, a valve stem connected to the valve member, the valve stem being rotatable relative to the valve body to adjust the valve member and to adjust a fluid flow rate through the fluid path, the position of the valve member relative to the fluid path being directly related to the fluid flow rate through the fluid path, the valve stem having a free end portion projecting from the valve body; a first fluid pressure sensor positioned to measure the fluid pressure of fluid entering the inlet of the valve body; a second fluid pressure sensor positioned to measure the fluid pressure of fluid exiting the outlet of the valve body, wherein a difference between the first and second pressures is the pressure drop across the valve; and a BTU meter assembly connected to the free end portion of the valve stem, wherein the valve stem is rotatable relative to at least a portion of the BTU meter assembly, the BTU meter assembly comprising a BTU body, a position sensor coupled to the BTU body and to the valve stem, the position sensor being configured to detect the rotational position of the valve stem relative to the BTU body, the BTU meter assembly having a controller coupled to the position sensor, to the first and second pressure sensors, and to the first and second temperature sensors, the controller being configured to determine the fluid flow rate based upon the pressure drop across the valve and the rotational position of the valve stem, and the controller being configured to determine energy usage of the heating or cooling device in real time based upon the flow rate and the temperature change across the heating/cooling device.