I have an old boiler from a house built in 1927. I just received my latest bill and it was $400.00. I checked the temp. settings and the high is set to 180 and the low is set to 125. What should this be set at to save money? Also does turning the temperature on the thermostat up and down or even off and on cost more money or not because it's gas? Also what would be my best option for a heat pump?