Natural Gas Properties and Furnace Heating Efficiency - Natural Gas is a popular fuel used for heating systems in America and other countries. If we look at the properties of natural gas and the heating efficiency of natural gas furnaces we will see that natural gas furnaces lose efficiency because of what is contained in natural gas as it is delivered to your home for consumption by your natural gas furnace. Natural gas in its raw form coming straight from the ground needs to be refined to remove impurities that should not be contained in natural gas. As you read below you will see that in the refining process moisture is removed from the natural gas however during the refining process some of the moisture in the natural gas remains and therefore this affects the efficiency of your natural gas furnace.
Natural Gas Properties and Furnace Heating Efficiency
Condensing furnaces always have a drain on them to drain away one of the byproducts of combustion which is water/moisture contained in the gas. This is why it is called a condensing furnace simply because it condenses all the moisture from the gas during the combustion process. I am certain there are people who have had a problem with a leaking furnace in the winter time where the drain became clogged or plugged and required someone to clear the condensation drain to clear the drain. This is the water that is condensed from the natural gas during the combustion process along with moisture contained in combustion air. Any moisture in the gas will affect the efficiency of the furnace. The fewer impurities in the natural the more efficiency you will get from the gas furnace.
Natural Gas Properties and Furnace Heating Efficiency | Properties of Gas
Natural gas is made up of over 70% methane among other gases and liquids including ethane, propane, and butane. Natural gas in its raw form as it is extracted from the ground also contains CO2, hydrogen sulfide, nitrogen, and water. When the natural gas is extracted from the ground it goes through a separation process at a separation facility designed to extract the other gases and liquids from the natural gas. After the natural gas is processed, an odorant is added to the natural gas for safety.
Natural gas in its raw form is colorless and odorless so an odorant is necessary for safety reasons. The odorant helps someone detect natural gas if there is a leak since natural gas is flammable and explosive in the right air mixture combinations. Natural gas is also lighter than air (with a specific gravity of .06 to .08 with air being 1) so it will accumulate in spaces that are higher up such as attics and other places if there is a leak versus LP which is heavier than air and considered more dangerous. The odorant smells like rotten eggs so if you ever smell something like rotten eggs around any natural gas piping or appliances you most likely have a leak and need to take action to turn the gas source off and get the leak repaired.
Natural gas does disperse quickly in the outside air however inside tight spaces or tight homes it can accumulate and be a danger to the occupants of the structure. You can see a comparison of natural gas versus propane in another article we wrote here.
Natural Gas Properties and Furnace Heating Efficiency | Combustion
Natural gas is also cleaner burning than other fuels used for heating and industrial processes such as generating electricity, therefore it is considered better for the environment than burning oil, coal or even wood. Natural gas is a fossil fuel that is derived from plants and animal remains from millions of years ago. Millions of years ago dead plants and deceased animals were buried under the ground and as they decayed they left behind gases and other fossil remains that we use today for things like natural gas and even oil.
The by-products of using fossil fuels including natural gas include CO2, nitrogen oxide, sulfur dioxide and carbon monoxide among some particles and moisture so the by-products of combustion from any fossil fuel including natural gas need to be properly vented and dispersed into the air for safety and health reasons as these by-products of combustion from fossil fuels can be very dangerous to humans and result in serious health issues and even death.
The benefits of natural gas over other fuels used for heating whether it is for industrial, commercial, or residential outweigh other fuels in safety and the clean burning of natural gas as compared to LP (Liquefied Propane) gas, coal, and even oil. Additional natural gas is delivered in a pipeline and is available in most urban areas of the country so natural gas does not require one to have a storage tank or have to wait for a delivery as does coal, oil, and LP.
Natural Gas Properties and Furnace Heating Efficiency | Conclusion
It is a fact that the gas that comes into your home contains approximately 3 to 5 percent impurities including moisture and these impurities take away from the efficiency of the gas furnace. The gas company does refine the natural gas at a refining facility however not all impurities are removed. It is simply impossible to remove 100% of the impurities without raising the cost of the cost gas to unaffordable amounts.
Natural gas furnace efficiency AFUE ratings have risen over the last 4 to 5 years however because of natural gas properties and the impurities contained in the natural gas it is impossible for a natural gas furnace to get 100% efficiency until natural gas furnaces become co-generation then it is unlikely the natural gas furnace will ever go over 95% to 98% efficiency.
Natural Gas Properties and Furnace Heating Efficiency
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