A furnace is a heating system that blows heated air through ducts and delivers the warm air to rooms throughout the house via air registers or grills. This type of heating system is called a forced warm-air distribution system. It can be powered by electricity, natural gas, or fuel oil.
Inside a gas- or oil-fired furnace, the fuel is mixed with air and burned. The flames heat a metal heat exchanger where the heat is transferred to air. Air is pushed through the heat exchanger by the “air handler’s” furnace fan and then forced through the ductwork downstream of the heat exchanger. At the furnace, combustion products are vented out of the building through a flue pipe. Older “atmospheric” furnaces vented directly to the atmosphere, and wasted about 30% of the fuel energy just to keep the exhaust hot enough to safely rise through the chimney.
Current minimum-efficiency furnaces reduce this waste substantially by using an “inducer” fan to pull the exhaust gases through the heat exchanger and induce draft in the chimney. “Condensing” furnaces are designed to reclaim much of this escaping heat by cooling exhaust gases well below 140°F, where water vapor in the exhaust condenses into water. This is the primary feature of a high-efficiency furnace. These typically vent through a sidewall with a plastic pipe.
Heating system controls regulate when the various components of the heating system turn on and off. The most important control from your standpoint is the thermostat, which turns the system or at least the distribution system on and off to keep you comfortable. A typical forced air system will have a single thermostat. But, there are other internal controls in a heating system, such as “high limit” switches that are part of an invisible but critical set of safety controls.
Like any heating or cooling system, proper furnace maintenance is the key efficient operation. When you choose us as your HVAC Service Company, we have a “Nate Certified” Comfort Specialist who will perform a preventive maintenance inspection on your furnace system to ensure a seamless operation.