With winter's chill settled firmly across much of America, safety experts are cautioning that this is the time of greatest fire danger.

Every home should have one or more smoke detectors, and this is a good time to check the batteries to make sure they are operating.An annual furnace inspection by a qualified contractor is important, even if the furnace is in use and seems to be operating well, the federal Consumer Product Safety Commission reports.

When the inspection is done, ask them to look at the venting system also - the flue and chimney - to make sure there are no blockages, from bird nests or debris for example. Venting problems can cause carbon monoxide to get into the house - a deadly gas that cannot be smelled or seen.

Heating systems are blamed for as many as 150,000 house fires annually.

The commission has put together a checklist to help people remember the various things to be wary of, and what to do about them.

Single copies are available at no charge, while they last, to those who send a postcard with name and address to Home Fire Safety Checklist, Consumer Product Safety Commission, Washington, D.C., 20207.

Supplemental heating systems - room heaters - pose an even bigger danger than central systems, the commission warns.

Here is a rundown of the most popular supplemental heating systems, their dangers and the precautions that should be taken, according to the CPSC:

-Kerosene heaters:

Most kerosene heater fires result from flare-ups, generally resulting from the use of contaminated or improper fuel. Most dangerous, the commission said, is the use of gasoline in a kerosene heater. That can lead to an explosion.

Kerosene heaters also can emit pollutants, which can accumulate in an enclosed area, the commission said. When using these appliances, make sure there is plenty of ventilation.

-Wood stoves:

Wood stores and fireplaces are blamed for nearly 100,000 house fires annually, with chimney fires posing the major danger.

Creosote builds up in the chimneys of these heating units and can later ignite, causing a roof or house blaze. Annual chimney cleaning is a necessity.

Wood stoves also can lead to burns and fires if not installed correctly, and the agency has established labeling standards to make sure buyers are aware of safe placement and use of these stoves. Local building codes also contain safety rules in many areas.

-Electric heaters:

Portable electric heaters are blamed for nearly 3,000 fires annually, and also can pose a danger of burns if touched.

These heaters should not be located in heavily traveled areas or places where children can come in contact with them. Never use an extension cord with an electric heater, and keep them away from water.

-Gas heaters:

Proper installation is essential to prevent both fires and the escape of dangerous gas fumes.