The thing that makes a communicating hybrid (gas furnace w/ electric heat pump) system so important is the management of the balance point. See, a standard hybrid heat pump system has what is called an outdoor temperature balance point or shut off where the heat pump quits and the gas furnace takes over. In the pacific northwest this is generally sized set at 30 or 35 degrees, however, when you buy a communicating hybrid heat pump system there is no set balance point.
What I mean is that instead of us having to tell the heat pump what it should do, we let the system decided at what temperature it will shut down the heat pump and let the furnace take over. This allows for some astronomical savings! Let me ask you this, how much fuel do you think you burn when the outside temperature is below 30 degrees?
The answer is A LOT! I have personally watched my Carrier Infinity Hybrid System float my heat pump balance point down to 9 degrees outdoor temperature. Below is a picture of my thermostat showing that it is 15 degrees outside and my heat pump is running on low stage…you do the math….