Just like a pinched garden hose that can't deliver a full amount of water from the spigot to a flowerbed, kinked or twisted duct work cuts the amount of heat that can flow from the furnace to the rooms where it is needed. Check the ducts to insure they are properly supported, don't sag, twist or bend unnecessarily, and have no gaps or breaks.

Leaks can be prevented by sealing ducts with a good mastic compound at the joints. Don't just rely on duct tape as a joint fastener; it will quickly deteriorate and lose its seal. For metal ducts, sheet metal screws should be used to hold sections together; flexible duct connections should be secured with metal or plastic bands.

California's Energy Efficiency Building Regulations now require duct work to be insulated, just like walls, ceilings and floors. Minimum requirements call for R-4.2 insulation around ducts located in attics and crawl spaces, but the Energy Commission suggests that insulating to a factor of R-8 or higher will significantly increase comfort and energy savings.

Regularly clean your air filters, fresh air intakes, supply vents and return grills. Dust and dirt cause your heating equipment to work harder. That means higher energy bills.