This past summer we moved into a home that was built in the early 1900s. The home has cast iron radiators and the water is heated by an oil burner and is controlled my a manual Honeywell thermostat. In my previous homes I have had programmable thermostats and set them lower during the night to reduce my energy bills. I am thinking about installing a programmable thermostat and do the same thing. However, in talking with some neighbors they seemed to think that would not be the best idea because of the nature of this type of heat system. They said that it would be better (use less energy) to keep the temp constant because with the water cooling down during the night it would take more energy to heat it back up in the morning than just keeping at a steady temp all night. It seems to me that it would use less energy by turning the temp down for those 6-8 hours during the night even though it would have to work harder to bring the water back up to temp. So which method is more energy efficient for this type of heat system?