Abstract: A bi-functional roof drain includes a housing forming a drain manifold and a drain outlet to connect to a drainage system. A vent pipe penetrates the housing and extends through the manifold. The top of the vent pipe is positioned a distance above the housing, which may be variable. With this drain, a method of retrofitting a roof drainage system to provide water drainage and system venting is also presented. This method includes removing an existing uni-functional roof drain from a deck penetration through the roof, and installing a bi-functional roof drain in the same deck penetration. The drain outlet is connected to the drainage system and the vent pipe is connected to the system that requires venting. The height of a top opening of the vent pipe of the bi-functional roof drain may be adjustable in relation to a surface of the roof.

Abstract: An overflow sensor adapted to detect water flow in a backup roof drainage system is provided. The overflow sensor comprises a housing, a water flow sensor, and a control module. The housing is configured to sealingly mate with the backup roof drainage system. The water flow sensor is coupled to the housing and positioned to detect a flow of water of at least two levels in the backup drainage system. The control module is in communication with the water flow sensor and includes an indicator activatable when the water flow sensor detects the flow of water in the backup roof drainage system. This indicator is latched on until reset.

Abstract: An inlet flow multiplier for a drain is provided. The multiplier includes a planar baffle having a mounting collar oriented perpendicular to the plane of the baffle. The collar has a pair of clamping flanges to allow it to be mounted to drains of varying diameter. The length of the baffle is substantially longer than the diameter of the drain to which it is mounted. In one embodiment, the length is approximately five times as long. The baffle is mounted so that it intersects the circumference of the drain. Optimally, the baffle bisects the drain opening. A bi-functional roof drain utilizing the inlet multiplier is also provided. Such a drain includes a primary drain and a backup drain pipe extending through and isolated from the primary drain. The planar baffle is attached via the mounting collar to the backup drain pipe to position the planar baffle above the top opening.