True or False: The minimum amount of natural gas needed in the furnace fuel/air mixture for proper burning is 4%.

The statement regarding the minimum amount of natural gas needed in the furnace fuel/air mixture for proper burning being 4% is accurate. A properly functioning gas furnace requires a certain concentration of gas mixed with air to achieve efficient combustion and avoid safety hazards.

In this context, gas furnaces are typically designed to operate within specific ranges of fuel-to-air mixture ratios, which ensure optimal combustion. A mixture with less than the required minimum gas concentration, in this case, 4%, can lead to incomplete combustion, resulting in lower efficiency and potentially dangerous conditions such as the accumulation of carbon monoxide. Therefore, maintaining at least 4% of natural gas in the mixture is essential for safe and efficient operation of furnace systems.

Other percentages mentioned do not align with this standard for efficient natural gas combustion within a furnace, as 3% is not sufficient, while 5% would likely be above the necessary minimum, depending on the specific design and requirements of the furnace. Thus, identifying 4% as a valid threshold is essential for ensuring proper furnace function and safety.