Most people think of winter as a chilly, damp time of year. While that might be the case outdoors, just the opposite often is true indoors. While your home's heating system can keep you warm during the winter, it can cause your house to become too dry.

Such a home can be the cause of a dry nose and throat and colds, not to mention what it does to your home. Wall paneling, wood trim and hardwood flooring can shrink and cause joints to open. You might even find that joints in wood furniture become loose. And, pianos have been known to go out of tune.

While it's true that dryness is more prevalent in the cold north, many homes throughout the country experience the same problems when the weather turns cold. However, more often than not, homes contain enough sources of indoor moisture (cooking, clothes drying, showering) to balance the moisture losses in winter and keep humidity at a comfortable level.

One of the most effective methods of dealing with dry home syndrome is to use a whole-house humidifier. In simple terms, a central humidifier supplies humidity to a home through the duct work in a forced-air heating system. Whenever the furnace blow kicks on, the low-voltage electrical circuit that operates the humidifier also turns on. The humidifier operates when a room-mounted moisture-sensing device, called a humidistat, detects that air in the home is too dry. The humidistat can be adjusted to control condensation on windows.

Whereas a humidifier might be the answer for a more healthful and comfortable home, be aware that there are other, less costly choices to first consider. For example, caulking and weather-stripping around doors and windows will help keep moisture in and prevent the home's interior from drying out so radically. This will cost less to install, and is a project most do-it-yourselfers can handle (a central humidifier might not be). And, in the long run, you'll save on your utility bill.

Installing a central humidifier involves several skills such as electrical, plumbing and sheet metal. If you have above average skills in these areas, it's a project you're likely to feel comfortable attempting. If you are certain that this is a task that is best left for a professional, contact a local heating pro for an estimate.

The price for a central humidifier (not including installation) ranges from $100 to $500, and includes all of the necessary installation components. While installation will vary from furnace to furnace, depending upon space and configuration, the general process is the same. The humidifier, including the ductwork, mounts on the heating ductwork near the blower. This is true for both furnaces and heat pumps. Homes with no ductwork or those heated by hot water or electricity cannot use a central humidifier. In these cases small localized units will need to be used.

There are three types of central humidifiers: bypass with a drain, bypass without a drain and spray type. The bypass type with a drain uses a bypass duct that runs from the supply side of the furnace to the humidifier mounted at the return air duct near the blower. The supply ducts provide heated air to the home while the return air duct draws in cool air that is to be heated. Consequently, warm air is circulated through a wet grid located within the humidifier. When this type of system is operating, water trickles through the grid, with the excess draining through a tube into a nearby floor drain.

The bypass without a drain operates much like the first with a few exceptions. Instead of excess water draining out through a tube, water resides in a pan and moistens a revolving element through which air passes. This requires a bit more maintenance as it needs to be cleaned frequently to prevent algae and bacteria from growing in the standing water.

The spray type injects a fine mist directly into the ductwork when the blower goes on. Homes located in areas where the water is hard (contains many minerals) should avoid this type of system because a white powder will build up on the blower, furnace burners, ductwork and perhaps on the furnace.

Humidifiers are not maintenance-free. Either at the beginning or end of the humidifying season, shut off the humidistat, the power to the furnace and the water supply. The inside of the housing and parts should be thoroughly washed with detergent and water to prevent the growth of algae, fungus and bacteria. Also, the humidifying element should be replaced annually.

And remember to turn the humidistat down and close the damper at the beginning of the cooling season if your home is equipped with central air conditioning.