Patent ID: 9631811
Date: 2017-04-25
CPC Classifications: F04D,F23L,F23N,F24H,H02K

Claim:
1. A furnace assembly comprising a non-condensing furnace with a draft inducer, the draft inducer comprising a permanent magnet electrically commutated motor and a draft inducer blower fan, the motor comprising a stator, a rotor, a motor cooling fan, and a controller, the rotor being rotatable relative to the stator, the motor cooling fan being operatively coupled to the rotor such that rotation of the rotor causes rotation of the motor cooling fan, the motor cooling fan being configured and positioned to move air in a manner to cool at least some components of the motor, the draft inducer blower fan being operatively coupled to the rotor such that rotation of the rotor causes rotation of the draft inducer blower fan, the controller being configured to selectively operate the motor in first and second different torque ranges of the rotor, the first torque range constituting a first torque and all torques within five percent of the first torque, the second torque range constituting a second torque and all torques within five percent of the second torque, the magnitude of the second torque being less than about seventy percent of the magnitude of the first torque, the controller being configured such that during normal operation of the furnace assembly the motor is not operable at any torques between the first torque range and the second torque range except during transitionary periods in which the controller switches operation of the motor between the first torque range and the second torque range or the motor transitions between on and off states.