I need to know basic operation procedures for my Lennox thermostat. I also have a hot water heater. I have two seperate thermostats to control hot water heat and air conditioning. I have the em. heat option available on my air conditioning thermostat. I am wondering what options I should use for the winter months and which to use for the in between (fall, spring). I live in MN. I am guessing the thermostat is between 10-15 years old. Thank you for your help.