Patent ID: 8146612

Claim:
A warewash machine, comprising: a housing at least in part defining a chamber for cleaning wares; a sump for collecting hot cleaning water that is recirculated in the chamber during cleaning; a drain line for draining cleaning water from the sump; a fresh water input system including at least a hot water input that receives hot water from a hot water source and a cold water input that receives cold water from a cold water source, the fresh water input system having a common input line in communication with the hot water input and the cold water input; a cold water input valve for controlling input of cold water into the common input line; a hot water input valve for controlling input of hot water into the common input line; the drain line and the common input line arranged in a heat exchange relationship to enable heat from cleaning water traveling through the drain line to transfer heat to water traveling through the common input line; a temperature sensor arrangement associated with the drain line for determining temperature of the cleaning water traveling through the drain line; a controller that receives input from the temperature sensor arrangement and is configured to control the cold water input valve and the hot water input valve such that, during a draining operation, (i) if cleaning water traveling through the drain line is above a preselected temperature, the controller opens the cold water input valve to allow water from the cold water source to enter the common input line and (ii) if cleaning water traveling through the drain line is below the preselected temperature, the controller closes the cold water input valve.