What About That Old Furnace!
Those older style atmospheric furnaces may be dangerous, (the ones with a pilot light.) Over the years the metal heat exchanger inside these older machines tends to deteriorate and can potentialy develope a crack. If this were to happen then combustion gases are able to mix with heated air that is then blown into the home. Some brands in particular have a bad reputation for cracking, call me for more information on these problem furnaces. I got a call last year from the head office of one manufacturer to stop telling the truth about their older products. If in doubt have it checked by a licensed HVAC technician.
This is why a carbon monoxide detector is a must if you have an older forced air furnace!