Types Of Gas Furnaces

 Furnaces have been around since time immemorial. The history of comfort heating can be traced back to the time of early men when camp fires were made for warming. Wood remained a constant fuel for a long time to light furnaces for heating houses. In the end of the 19th century, low cost cast iron radiators were invented. In this a coal fired boiler in the basement delivered hot water or steam to radiators in every room. In 1885, Dave Lennox built the first riveted-steel coal furnace. These transported heat by natural convection through ducts from the basement furnace to the rooms above. In 1935, forced air furnaces were designed that used coal as a heat source and an electric fan for distributing the heated air through duct work within the home. Shortly after this gas and oil fired furnaces came into being. In the modern times gas furnaces are a preferred mode of heating because of their efficiency and reliability.

 Gas furnaces can be classifies into three categories single-stage, two-stage, and modulating furnaces.

Single-staged furnaces:
Also known as standard furnaces, these heating systems have a gas valve that opens and closes to allow the flow of the gas into the burner for ignition. The speed of gas flow to the burner is singular. The AFUE of single stage gas furnace on the average is around 80%. If you live in mild region then these units are enough to meet your heating needs. But they are not quite effective to save on monthly energy costs.

 Two-Stage Furnace: The notable difference between a single-stage and a two- stage furnace is that in the latter you can adjust the valve’s flow of gas to low and high, or "half power" and "full power." This adjustment happens according to the home’s heating needs. The system communicates with the thermostat to know the heating requirements.

When you run the system on half power, a system with an 80,000 British thermal unit (Btu) will deliver 40,000 Btus. It will continue to serve so unless it gets a signal from the thermostat to run on full power. Only then the valve will open widely to increase the flow of gas.

An advantage of these systems is that on half power they have an extended heating cycle. This ensures a better distribution of heat and warmer homes. The AFUE rate of these furnaces is around 90 percent.

 Modulating Furnace

These furnaces have a modulating gas valve and a variable-speed blower. The furnace starts with a gas flow of 100 % and fan rotation at 0%, the valve opening then gradually reduces and the blower speed increases until maximum efficiency is reached. Since the fan and burner never runs together in full capacity, the cycling on and off is almost eliminated. . These are very fuel-efficient units.

If you are looking for low operating cost go for modulating furnaces. Homeowners in cold regions benefit a lot from these as they have a superb control over gas consumption and saves energy through efficiency.

 Besides these furnaces can also be classifies as conventional furnace and condensing furnace. Convectional furnaces are traditional furnaces that exhaust the hot combustion gases fast that creep through flue and goes out your house. The condensing furnace is a more energy efficient option that sends combustion gases again to second heat exchanger. Here it is condensed and the heat generated in the process is captured for heating purpose. The water condensate vents out of the furnace's heat exchanger and the flue gases escape from a plastic PVC pipe.



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