Patent ID: 7081728

Claim:
A heat recovery apparatus with an adjustable setpoint temperature comprising: an induction motor equipped with a heat recovery unit employing a liquid coolant that is pumped through the heat recovery unit; a switching device coupled to the motor and being switchable between a first state wherein significant current flow through the motor is prevented and a second state wherein current flow through the motor is substantially undisturbed; user controls for providing motor control input signals; an input for receiving liquid coolant setpoint temperature signals; a controller responsive to the motor control input signals to control the operation of the motor; said controller further being operable to control the operational efficiency of the motor by switching the switching device between said first and second states in a predetermined sequence so as to induce a phase angle delay in an alternating current supplied to the motor; and said controller being further being responsive said temperature setpoint signals to vary the operational efficiency of the motor and thereby the heat output of the motor to achieve a liquid coolant setpoint temperature determined by said liquid coolant setpoint temperature signals.