1. Make sure all the steam piping in the basement is insulated. The pipe insulation should be a minimum or 1" wall thickness. No need to insulate the return pipes. If you have insulation removed from the steam pipes for basement heat replace it. This is an expensive way to heat even a small area. See adding a baseboard loop in your basement, then click the back button.
2. Verify the near boiler piping is correct. Incorrect near boiler piping produces short cycling, noisy system or wet steam, all of which produce higher fuel bills.
3. Verify all radiator vents are working properly. NO AIR VENT SHOULD EVER VENT LIVE STEAM!!!!
4. The main line vents also need to work. Their job is to get steam to the end of the main as fast as possible. This may require the use of two or more main line vents in the same location. See vents on the above link.
5. Reduce the steam pressure. The Cut-out or main steam pressure should never be set above 2 psi. Most systems today are operating lower than 2 psi even in the ounces range. If the setting is too low it may cause short cycling which will increase fuel consumption.
6. Maintain the water level where the manufacturer suggests as the Normal Water Line (NWL), even if you have an automatic water feeder. Remember an automatic water feeder does not take the place of you maintaining water levels. The automatic water feeder is for use when you are not able to check and maintain the proper level.
7. Replace your thermostat with an electronic thermostat. The old thermostat calibration may inaccurate or a dust buildup on the mercury bulb affecting the accuracy of the thermostat. It may cause the heat to run longer than necessary or causing an uncomfortable temperature swing. Make sure you set the thermostat for a steam system in the menu or dip switches on the thermostats.
8. Make sure the return lines are in good condition and flowing freely.
9. Clean and inspect the boiler annually. Check system and vents for leaks. This should include a gas pressure check or fuel pump pressure check and combustion analysis.
10. Replace the boiler with a newer steam boiler if the existing boiler is over 10 years old. The older the boiler the less efficient it is. If the boiler is a coal converted boiler to natural gas or oil this is a must. The large flue passes allows too much heat to leave the boiler and never touch the iron. Therefore, less heat transfer.