Abstract: A fluid heater employs a vapor compression cycle system. The vapor compression cycle system includes an evaporator, at least one condenser and a working fluid. The fluid heater includes a fluid conduit which forms a tube-in-tube heat exchanger with the condenser to effect heating of the fluid. A sensor is positioned at the condensing zone of the working fluid, to determine the temperature of the working fluid at the condensing phase of the vapor compression cycle. The output of the sensor is used to control the flow rate of fluid through the fluid conduit in order to achieve a desired target temperature of the fluid leaving the conduit.

Abstract: The present invention relates to a fluid heater comprising a vapour compression cycle system. The vapour compression cycle system includes an evaporator, at least one condenser and a working fluid. The fluid heater also includes a fluid conduit through which a fluid can pass in thermal contact with the condenser to allow, via heat exchange between the fluid and the working fluid, the heating of the fluid. A sensor providing an output from which the temperature of the working fluid at the condensing phase of the vapour compression cycle system can be determined is also included in the fluid heater. The fluid heater system has a flow rate controller to control the flow rate of fluid through the conduit. The fluid heater is controlled using a controller operatively connected with the flow rate controller to vary the flow rate of fluid through the conduit reliant on the output from the sensor to achieve a desired target temperature of the fluid leaving the conduit.