Quite frankly the Nest thermostat just falls short in many ways, especially if you have a 2 or 3 stage heating solution. First, Nest does not know the heat loss of the structure. Second, while Nest may know you have a 2 or n-stage solution it has no clue how many BTU each stage produces. Third, Nest does not use the outside temperature or create a Design Temperature Difference for your locale so it basically guesses at when to invoke past stage 1 heat. It is a very expensive solution with a half baked design that could have easily been resolved by having the proper HVAC parameters to determine the heating and cooling requirements of your home. Other than the ability to monitor and adjust the temperature remotely it is pretty much worthless in my opinion. If Nest is a learning device it must have went to school on the short bus. It was not designed by people who understand HVAC and the heat losses and gains of a structure. What is 100% true is that if you don't know the difference between outside and target inside temperature (DTD), the heat loss of the structure in BTU and how much heat or cooling the HVAC equipment can produce and on what stage you are wasting the people's time and certainly their money. If the Nest development group wants to know what to do to create a solution that works, saves the customer money by optimizing the heating deployment give me a call. I'd be happy to help.
