Proper maintenance can have a big effect on fuel bills and should be performed on a routine basis.

Clean or replace air filters regularly.

 Clean registers. Warm-air supply and return registers should be kept clean and should not be blocked by furniture, carpets, or drapes.

 Keep baseboards and radiators clean and unrestricted by furniture, carpets, or drapes.

 Bleed trapped air from hot water radiators. Follow prescribed maintenance for steam heat systems, such as maintaining water level, removing sediment, and making sure air vents are working. Check with your heating system technician for specifics on these measures and use caution: steam boilers produce high-temperature steam under pressure.

 Tune up your system. Oil-fired systems should be tuned up and cleaned every year, gas-fired systems every two years, and heat pumps every two or three years. Regular tune-ups not only cut heating costs, but they also increase the lifetime of the system, reduce breakdowns and repair costs, and cut the amount of carbon monoxide, smoke, and other pollutants pumped into the atmosphere by fossil-fueled systems.

 Seal your ducts. In homes heated with warm-air heating, ducts should be inspected and sealed to ensure adequate airflow and eliminate loss of heated air. It is not uncommon for ducts to leak as much as 15-20% of the air passing through them. And leaky ducts can bring additional dust and humidity into living spaces. Thorough duct sealing costs several hundred dollars but can cut heating and cooling costs in many homes by 20%.

 Check for wasted fan energy. If your furnace is improperly sized or if the fan thermostat is improperly set, the fan may operate longer than it needs to. If you're getting a lot of cold air out of the warm-air registers after the furnace turns off, have a service technician check the fan delay setting.

PLEASE NOTE: ACEEE strongly recommends against modification of any gas-fired appliances, including furnaces, boilers, room heaters, water heaters, and clothes dryers. These appliances are tested and certified to operate safely only as designed and manufactured by the original equipment manufacturer. Any unauthorized alterations may jeopardize your safety by leading to fire, explosion, shock, or carbon monoxide poisoning. Be wary of contractors selling modifications to gas-fired heating appliances and consult with the original manufacturer or manufacturer's local representative before making any alterations. 

(www.aceee.com)