| 摘要 |
A bi-functional roof drain (10) includes a housing (12) forming a drain manifold (18) and a primary drain outlet (24) to connect to a primary draina ge system. A backup drain pipe (28) penetrates the housing (12) and extends through the manifold (18). The top (30) of the backup drain pipe (28) is positioned a distance above the housing (12), which may be variable. With th is drain a method of retrofitting a roof drainage system to provide primary and backup water drainage 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 (10) in the same deck penetration. The two drain outlets are connected to the primary and backup drainage syste m. The height of a top opening (30) of a backup drain pipe (28) of the bi- functional roof drain (10) may be adjustable in relation to a surface of the roof.
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