The contractor should install a computerized thermostat with it. This thermostat, coupled with the electronic controls in the new furnace, will maintain even room temperatures. The efficiencies of these condensing models range from about 90 percent to more than 95 percent. These models are very efficient and so little heat is lost in the flue gases that a chimney is not needed. With no need for a new chimney liner, a condensing furnace is often cheaper to install than a less efficient model.
Some models also offer sealed combustion for better efficiency.
The combustion air is drawn in from outdoors through another plastic pipe instead of being drawn from inside your house. Being sealed, there are fewer indoor drafts, less noise and less chance of hazardous backdrafting. This type of blower is needed if you want the best central air-conditioning too. In all but the coldest weather, the gas burners operate at a low heat level. This allows the furnace to run more continuously with fewer uncomfortable on and off cycles.