Which condition is vital for a plumbing vent to keep trap seals intact?

To ensure that trap seals remain intact in plumbing systems, maintaining positive pressures within the venting system is essential. Plumbing vents allow air to enter the drainage system, which prevents the formation of negative pressure as wastewater flows through the pipes. This negative pressure can cause trap seals to be siphoned or pulled out, leading to potential sewer gases entering the indoor environment.

When the system maintains positive pressure, it supports the balance of air, allowing traps to function effectively without losing their water seal. Proper venting helps to avoid situations where traps can be emptied through siphon action, thereby ensuring a barrier against sewer gases.

Conversely, conditions such as excessive heat, cold temperatures, or high humidity do not provide the necessary support to maintain the proper function of traps within a vented system. Therefore, having a consistently positive pressure is crucial for preserving trap seals and ensuring the safety and effectiveness of plumbing systems.