Removed old style thermostat replaced with Nest learning 3rd Gen. It used to be that the therm would call for heat and the fan would run at same time. Now the boiler turns on but I need to manually start the fan. I don't understand. I set the system up for heat only because the instructions say to set up for "now". The old one controlled heat and cooling. I live in NY so AC units are covered up. What is the solution to this.
