A heating system for a vehicle having a power plant with a power plant coolant loop, and a method of operation, is disclosed. The heating system may include a HVAC module and a heater core coolant loop. The HVAC module includes a heater core. The heater core coolant loop includes a three-way valve having an inlet engaging the heater core for receiving a coolant, a first outlet that directs the coolant back into the heater core coolant loop, and a second outlet that directs the coolant into the power plant; a coolant pump for pumping the coolant through the heater core coolant loop; and a coolant heater located upstream of the heater core that selectively heats coolant flowing therethrough. Also, a coolant line receives the coolant from a heater core outlet of the power plant and directs the coolant into the heater core coolant loop.