Orifice Size on a Gas Furnance
The orifice size in a gas furnace has a direct relationship to the furnace's energy efficiency. The gas burner orifice is simply the opening through which gas flows. The orifice size is based on a number of factors and is usually specified by the manufacturer. Therefore, replacing the orifice in a gas furnace deserves considerations. Does this Spark an idea?
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Energy Efficiency
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If you want to increase your gas furnace's energy efficiency while going through the process of changing its gas burner orifice, then reduce the size of the orifice. Doing so decreases the furnace's heating capacity but increases its energy efficiency overall. If you decide to make that modification, however, check your area's building codes ensure you won't violate them. Also, a qualified technician should perform the replacement. The work usually costs less than $100 and may save you up to 15 percent on your energy costs, as of early 2011.
Energy Output
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The size of the furnace's gas burner orifice affects the furnace's energy output. The energy output is measured in British thermal units (Btu). Generally, the higher the Btu, the larger the furnace and the more gas it requires to work properly. The orifice size also relates to Btu because it determines the outflow of the gas into the furnace system. Furnaces with a high energy output have a larger gas burner orifice than furnaces with a lower energy output.
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Measurements
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Gas furnace orifice openings often are measured in millimeters, although they may be expressed as a fraction of a standard inch. Gas usage increases as orifice size increases. Btu used per hour also increases as orifice size increases. The Btu is significantly higher with the use of propane gas than with natural gas because propane usually requires a larger opening.
Effects
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Decreasing a furnace's gas burner orifice size is not as much of a problem as increasing the orifice's size. The orifice releases gas from the Venturi tube, creating a cone that should match the tube's shape, which allows the gas to mix with the correct amount of air so that it can burn. If the orifice is too large, then it may release too much gas, creating a back-draft that causes the furnace to stop working correctly. If the orifice is too small, then too little gas may mix with air, which makes the furnace malfunction.
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