Home Inspection State Practice Exam

If a natural gas system is supplied with propane gas, what is the likely outcome?

1. The flame will be too high unless a smaller orifice is installed

2. The system will not function at all

3. The flame will be too low for proper heating

4. No changes will be observed

The correct answer is: The flame will be too high unless a smaller orifice is installed

When a natural gas system is supplied with propane gas, the combustion characteristics differ significantly between the two fuels. Propane has a higher heating value and different combustion properties, which means that it tends to produce a higher flame temperature and a more intense flame compared to natural gas. If the propane is introduced into a system designed for natural gas without any adjustments, the existing orifices, which are sized for natural gas, will allow too much propane to flow through. This can result in a flame that is too high and could potentially lead to unsafe operating conditions or damage to the appliance. For safe and efficient operation, it’s essential to replace or adjust the orifices to accommodate propane's specific requirements. This involves installing a smaller orifice designed for propane in order to control the gas flow and decrease the flame height to an appropriate level for the specific appliance being used. Therefore, the conclusion that the flame will be too high unless adjustments are made directly correlates to the differences in fuel properties and highlights the importance of proper equipment calibration when switching fuel types.