What is the maximum infiltration rate that can be used in the known air filtration method for indoor combustion air?

The maximum infiltration rate used in the known air filtration method for indoor combustion air is crucial for ensuring safety and efficiency in gas appliances. The accepted standard for infiltration rates indicates that 0.60 air changes per hour (ACH) allows for optimal combustion while preventing backdrafting and other safety hazards.

This rate ensures that there's sufficient combustion air available for appliances, thereby promoting complete combustion and minimizing the risks of carbon monoxide and other harmful gases. It's important to maintain this specific rate to balance indoor air quality with the operational needs of gas appliances. Air infiltration rates higher than this threshold could lead to inadequate combustion air delivery, which can adversely affect appliance performance and safety.

The other rates, such as 0.50 ACH, 0.55 ACH, or 0.65 ACH, either fall below or exceed the optimal range suggested by current standards in gas fitting practices. Consequently, the selected answer reflects the necessary balance between maintaining efficient combustion and ensuring the safety of indoor environments.