Multi Stage Heat Pump What Is A Multi-stage Heat Pump?

What is a multi-stage heat pump? - multi stage heat pump

I have 2 thermostats in my house, in the 2nd Stock control with 2 lights, green and red. green for "aux heat" and red hot for 'em. Can someone explain what is and what is it all about?

the thing is, when set to heat only the green light lights up and half the time blowing hot air and warm air will stop, but continues to fresh air and circulation is never completely off. if they "aux heat" (red light) is set, it will blow hot air continuously, but someome told me that "heat" when it's cold outside, and you should not wear all the time, because (they consume so much energy?). Is that true?