When installing a Category IV, two-pipe vent system, the elbow for the combustion air intake should be positioned how?

In a Category IV, two-pipe vent system, the proper positioning of the elbow for the combustion air intake is crucial for optimal performance and safety. When the elbow is pointed downward, it allows for effective drainage of any condensate that may form within the venting system. This is important because Category IV systems, which are high-efficiency appliances with a condensing heat exchanger, often produce acidic condensate as a byproduct of combustion.

By directing the elbow downward, any moisture that accumulates can flow away from the combustion air intake and not interfere with air delivery or the functionality of the system. This positioning ensures that the combustion air remains free from contaminants and that the system operates efficiently. Proper drainage helps prevent corrosion within the venting system and extends its lifespan, thus contributing to the overall reliability of the gas furnace installation.