Natural gas furnaces are the most popular style of heating system in this country. As far as the pricing for different types of heaters, furnaces are fairly reasonable. They also provide the opportunity to incorporate a central cooling system. Leading manufacturers now offer gas furnaces equipped with variable speed technology which achieve up to 98% AFUE ratings. A furnace relies on a duct system to carry heated air to the rooms in the home. There are some major drawbacks to this method of heating. Heat naturally rises. As the hot air pours from the vents, it tends to rise straight up to the ceiling, where it remains until it cools. It then drops down so that the coolest temperature in the room is near the floor. Because the highest temperature is up near the ceiling, the furnace needs to work a lot harder and run longer to create a warm and comfortable living space. The heat also sucks moisture out of winter air that is already extremely dry, leading to concerns with insufficient humidity. To prevent health concerns and property damage, it’s a good idea to invest in a humidifier to counteract the effects of the furnace. The duct system often harbors contaminants such as dust, pollen, dander, bacteria and mold growth. There can even be decomposing rodents inside. Every time the furnace operates, the air passes through the ducts, picking up harmful allergens and spores and spreading them to every room in the house. Flu-like symptoms, respiratory infection, headache and aggravated symptoms of allergies and asthma are a few of the consequences. There’s also the problem with energy losses from ductwork. The typical duct system sacrifices thirty percent of conditioned air to holes, leaks at the seams and improper design.