Maintenance Saves Money

The following maintenance should be provided by a heating system professional.

All systems:

Check the condition of your vent connection pipe and chimney. Parts of the venting system may have deteriorated over time. Chimney problems can be expensive to repair, and may help justify installing new heating equipment that won't use the existing chimney.
Check the physical integrity of the heat exchanger. Leaky boiler heat exchangers leak water and are easy to spot. Furnace heat exchangers mix combustion gases with house air when they leak—an important safety reason to have them inspected.
Adjust the controls on the boiler or furnace to provide optimum water and air temperature settings for both efficiency and comfort.
If you're considering replacing or retrofitting your existing heating system, have the technician perform a combustion-efficiency test.

Forced Air Systems:

Check the combustion chamber for cracks
Test for carbon monoxide (CO) and remedy if found
Adjust blower control and supply-air temperature
Clean and oil the blower
Remove dirt, soot, or corrosion from the furnace or boiler
Check fuel input and flame characteristics, and adjust if necessary
Seal connections between the furnace and main ducts.

Hot Water Systems:

Test pressure-relief valve
Test high-limit control
Inspect pressure tank, which should be filled with air, to verify that it's not filled with water
Clean the heat exchanger.

Steam Systems:

Drain some water from the boiler to remove sediments and improve the heat exchange efficiency
Test low-water cutoff safety control and high-limit safety control
Drain the float chamber to remove sediments, which will prevent the low-water cutoff control from sediment clogs
Analyze boiler water and add chemicals as needed to control deposits and corrosion
Clean the heat exchanger

http://www.energy.gov/energysaver/furnaces-and-boilers