I did the same thing over the summer, except I was out of the country for exactly a month. I have a Navion Combination boiler. Connected to 2 nest that control the heat. I do not have central air. I only have window units. No one used the gas or electricity during that month. The only thing that I turned on (at night from 9PM-6AM) Were my Nest Cameras. I still got a bill for 130.00.