What maintenance practice is essential for venting pipes in relation to their slope?

For venting pipes, it is critical that they slope down toward the furnace. This practice ensures that any condensate that may form within the piping due to temperature changes can effectively drain back to the furnace, preventing blockages and maintaining the proper functioning of the venting system. If the pipes were to slope upward or remain level, it could lead to a buildup of condensate, which may result in leaks, corrosion, or even a failure of the venting system.

Maintaining an appropriate downward slope also amplifies the system's efficiency by allowing the byproducts of combustion to flow freely and exit the home as intended. This is especially vital in high-efficiency gas appliances where condensation is a typical occurrence. Proper venting is essential for both safety and performance, ensuring that harmful gases are expelled outside and do not accumulate indoors.