Many homeowners might wonder whether it is easy to simply convert their gas grill to a propane device or vice versa. The size of the orifice in gas versus propane grills is one of many changes that would need to be made. The orifice in natural gas appliances is bigger because it operates at a lower pressure than propane. If you're converting your appliance to a different fuel source, you will need to compensate for the pressure change to avoid danger and damage.

Man pouring charcoal into grill
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Converting your grill from one fuel type to another must be done carefully.

Orifice Comparison

An orifice is the opening in the fuel line that feeds your grill's burners. The orifice composition is not significantly different between propane and gas grills. In both cases it is generally made of brass and is threaded to fit the end of a fuel hose. But the size of the opening is always different for the two fuel types because it is directly related to the pressure of the fuel being injected. Natural gas orifices are always larger than those for propane because natural gas operates at a lower pressure.

Orifice Size

You can open up your grill and find the size stamped on the orifice fitting, which describes the diameter of the small hole drilled into it. The size label is based on the size of drill bit used to make the hole. For example, a #56 orifice was drilled with a #56 drill bit. The correct orifice size is determined by the pressure and volume of the gas, so re-drilling this hole is a delicate process. Since smaller bit sizes equate to larger holes, natural gas orifices range from #54 to #31 while propane orifices range from #62 to #48.

Other Considerations

There are many components to consider when converting your grill's fuel type. An incorrect orifice size can damage the burner and other parts of the appliance and should only be altered by a professional. Control valves regulate how much gas is transmitted to the burner through the orifice, so they affect the orifice's output, regardless of orifice size. If you convert your propane grill to natural gas, the control valve may not supply enough heat through the orifice, even if the orifice is the correct size. The regulator controls the pressure of the fuel and differs between propane and natural gas. This must be converted only by a licensed professional.

Propane Versus Natural Gas

The components of your grill are designed and set to run with a single type of gas supply although some manufacturers may offer a conversion kit. It is not a simple procedure to convert to a different fuel type, though many consumers mistakenly believe that simply drilling a new orifice will do the trick. Attempting a conversion may void your grill's warranty. Conversions require the replacement of regulators, burners, orifices and sometimes the venting components. It may be more worthwhile to buy a new grill rather than attempt a conversion.