What is the minimum horizontal separation recommended between exterior supply and exhaust termination hoods?

The minimum horizontal separation of 6 feet between exterior supply and exhaust termination hoods is recommended to prevent potential issues associated with cross-contamination of air. When supply and exhaust systems are too close, there's a risk that the exhaust, which may contain pollutants or other undesirable elements, can interfere with the fresh air being supplied to a space. This separation helps ensure both systems operate efficiently and effectively, facilitating proper ventilation and maintaining air quality within buildings.

Maintaining this distance is also important for preventing back-drafting issues, where exhaust gases could inadvertently be drawn back into the building's supply air, compromising indoor air quality. The 6-foot guideline strikes a balance between practicality and performance, making it a standard practice in insulation and ventilation design.