Gas Furnace FactsGas Furnace Facts - Gas Furnaces are the most used types of the heating appliance for our homes and businesses and modern gas furnaces range in efficiency ratings from 79% to 98%. Gas furnaces can either use propane or natural gas for fuel. That largely depends on whether natural gas is available at the location of the appliance.

Propane is used in rural areas and in urban areas where the natural gas pipeline infrastructure is not available. Natural gas is delivered via pipeline, while propane is delivered via trucks and pumped into tanks. Tanks locations are on the premises near the gas furnace. The gas furnace that utilizes the propane for fuel needs a fuel supply. Therefore, the proximity of the tank.

Gas Furnace Facts | Fuel for the Furnace

The other differences between propane and natural gas are propane. Propane is heavier than air, while natural gas is lighter than air. The BTU rating between propane and natural gas is different, with propane offering more BTUs in comparison. The size of piping used to deliver the two different gases to the appliances. Finally, the pressures of the gases at the point delivery to the appliances. Natural gas produces 1,000 Btu’s of heat per cubic foot burned. Propane produces about 2,500 Btu’s of heat per cubic foot.

Propane or Natural Gas? Gas Furnace Facts

Natural gas versus propane facts - In comparison studies, natural gas is considered the cheaper alternative by far than propane as far as fuel usage, and production of heat is concerned. In different comparison studies, it cost nearly 200% more to produce 90,000 BTUs of heat with propane over natural gas. That makes natural gas a more attractive option.

It is a factor when considering whether to purchase a natural gas furnace or a propane furnace. They are the same except when the appliance arrives on site. It is converted to propane using a propane conversion kit provided by the manufacturer if the gas furnace is going to use propane for fuel.

The only issue in deciding between a natural gas furnace, or a propane gas furnace is the availability of the fuel. Natural gas is not available in every location. Furthermore, this is the reason why many people have propane gas furnaces for heating systems, cooking, and heating water.

If you are wondering which is better, Natural Gas or Propane, please see our article, Natural Gas Versus Propane

Scientific Definitions | Gas Furnace Facts

Natural gas: A gaseous mixture of hydrocarbon compounds, the primary one being methane, but commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxide, nitrogen, hydrogen sulfide, or helium. It is formed when layers of decomposing plant and animal matter are exposed to intense heat and pressure under the surface of the Earth over millions of years. The energy that the plants originally obtained from the sun is stored in the form of chemical bonds in the gas.1

Propane (C3H8): A straight-chain saturated (paraffinic) hydrocarbon extracted from natural gas or refinery gas streams, which is gaseous at standard temperature and pressure. It is a colorless gas that boils at a temperature of -44 degrees Fahrenheit. It includes all products designated in ASTM Specification D1835 and Gas Processors Association specifications for commercial (HD-5) propane.2

Safety and Regulation | Gas Furnace Facts

Gas furnaces are regulated for installation purposes. It is necessary for safety reasons to obtain a permit before installing a new gas furnace. Installations of new gas furnaces are typically regulated by the Mechanical Code along with the Fuel Gas Code. Furthermore, it is important to check with local municipalities to ensure all the proper procedures are followed for the proper and safe installation of gas furnaces.

Gas Furnace Facts - Gas Furnace Types

There are many gas furnace types to describe or classify gas furnaces. There are upflow gas furnaces, downflow gas furnaces, lowboy gas furnaces, and horizontal flow gas furnaces.

  • Horizontal flow gas furnaces can be either left or right or right to left gas furnaces.
  • Another type of gas furnace is a package unit gas furnace, which is usually a package unit with an air conditioner all in one unit. Everything sans the duct system is all in one gas furnace and air conditioner unit.
  • Wall and Floor Furnaces
  • Upflow gas furnaces have the airflow enter the bottom of the unit and supply hot air out the top of the unit usually into a duct plenum for delivery of hot air throughout the duct system.
  • Downflow Gas furnaces airflow enters the top of the gas furnace and delivers hot air out the bottom again usually into a ducted plenum for delivering throughout the duct system.
  • Lowboy gas furnaces are small gas furnaces designed to be fit tight areas like closets or other areas with limited space.
Delivery of Air for the Furnace

The delivery of air throughout the duct system for a horizontal flow gas furnace depends on the way the horizontal gas furnace is installed – left to right or right to left. Package units can be downflow for rooftop gas furnace installations or horizontal flow for installation on the ground just outside the structure where the gas furnace package unit is installed. Additionally, there are also gas-fired radiant heaters and gas furnace unit heaters for installation in garages and big open areas where a duct system is not appropriate for the installation of a gas furnace.

Gas Furnace Facts - Gas Furnace Components

Every gas furnace needs the following components to work. First, a gas furnace needs a gas line or a fuel source. Depending on the type of gas furnace will depend on the type and size of the fuel line used. Lastly, all these considerations are usually made by the installing contractor and comply with the National Fuel Gas Code and local regulations for the sizing and installation, including the type of materials used for the fuel line. There are many other gas furnace components, some described and some of our other articles.

The next component is the gas valve. The gas valve is like a switch, and it opens and closes on a command from a control usually the thermostat. The gas valve delivers gas into a manifold, and the manifold delivers gas to the burners.

The burners have an ignition system to ignite the gas. Once the gas ignites, it burns in a heat exchanger. The heat exchanger is designed to keep the combustion processes and gases apart from the heated air. Separate from the airflow stream that is delivered to the home or business. Finally, the typical ignition system for gas furnaces can either be a standing pilot or electronic ignition.

Keeping the combustion gases and the airflow stream apart is essential. Furthermore, combustion gases contain many noxious gases that are harmful to health, including carbon monoxide.

Other gas furnace components include the blower motor and blower assembly, the venting system for properly venting the combustion gases, a forced combustion air blower, and many safety controls to ensure the gas furnace is safely operating.

Gas Furnace Facts - History

The Romans originally invented the furnace around 1200 BC. The Romans used early furnaces for producing metal products. Most likely for tools and ornaments but to fuel their armies with weapons. Consequently, these early furnaces led to central furnaces to keep their homes warm when the weather turned cold.

Gas Furnace Facts | Video

The following video concerns one safety control, which is the pressure switch. The pressure switch in a gas furnace monitors the function of the combustion blower. If the combustion blower fails, the pressure switch will kill the gas furnace, especially the process of combustion. The gas furnace troubleshooting article can be found here.

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Gas Furnace Facts