Every year you dread turning on your central heating for the first time because it smells musty and stuffy, or worse. After a few days it finally goes away -- or maybe you just get used to it. Now there's something you can do about it. First make sure ducts under floors aren't touching the ground, allowing water to enter. And that ducts are well insulated to reduce condensation. Either way, standing water and vapors quickly become a raging science experiment where mildew, fungus and bacteria grow at will. Next, remove furnace filters and turn the fan on -- not the burners, just the fan. Here's the solution. Fill a spray bottle with liquid bleach. If you wish, add a little cologne or fragrance. Then spray it into the air ducts at the furnace. The fan will force and carry the disinfectant and sweet-smelling fragrance throughout the duct system, killing all mildew, fungus and bacteria along the way. It will leave your home smelling like a fresh, spring day. And that's the On The House tip for today.