When venting Category I furnaces, where is the appropriate location to adapt to a larger vent pipe?

The appropriate location to adapt to a larger vent pipe for Category I furnaces is two feet above the furnace connection. This specific elevation is crucial because it helps ensure that the venting system operates effectively by allowing the products of combustion to flow upward and away from the furnace without obstruction.

When venting, it is essential to maintain proper draft and prevent backdraft conditions. By transitioning to a larger vent pipe two feet above the connection, you provide a smooth transition that minimizes turbulence and allows for an effective drafting of combustion gases. This height helps avoid any condensation issues that could occur if the system were to be too close to the furnace, thus reducing the risk of corrosion.

This practice aligns with common industry standards and guidelines for venting Category I appliances, ensuring safety and efficiency in the overall heating system.