Fall
Have a qualified service technician check for carbon monoxide leaks in your furnace every fall.  (See the service section for more information on the hazards of carbon monoxide)
Keep snow cleared away from your outside gas meter.  It needs to vent to function properly.
Fall - Summer
Change your furnace filter at least twice annually.
Annual safety check of your heating and cooling system can save you from costly repairs due to neglect.
Turn your heating and cooling systems on early in their respective seasons to be sure they are in good working condition.  You'll beat the service rush with a pre-season clean and check.
Keep your heating and air vents clear from obstruction.  If air has to force its way out, your system has to work harder.
Install a programmable thermostat and get rid of your old inefficient one.  This will allow you to have the temperature set at the most efficient setting while you are tucked away in your covers at night time, or away from your house during the day.
Weatherstrip doors and windows. Why heat/cool the outdoors?
Turn off incandescent lights when you are not using them and use low wattage light bulbs in halls and other places where no close up tasks occur.
If possible, switch to fluorescent lights where you can.  They are capable of producing about 4 times as much light per watt as incandescent lights and last longer, which will provide you overall with savings.
Don't peek at your food in the oven while you are cooking it unless you have to.  Each time you open the door, 23% of the heat is lost.
Disconnect your garden hose in the fall  to prevent the outside sillcock from winter freeze.
Turn off your water heater when you'll be away from home for a vacation or a long period of time.
Make sure you don't have leaky faucets.  A simple drip can equate to over 250 gallons of water a month.
Candles are nice, but they cause soot.  One candle with a ceiling fan blowing or a central air conditioner circulating the air can create stains throught the entire house.
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