Page 568 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

The City & Guilds Textbook: Plumbing Book 1

Invert connection above the spill-over level

Ventilation pipe

Appliance
spill-over level

Branch discharge pipe 300mm
max.

p Figure 9.9 Branch ventilating pipe rules

Stub stack system: low-level WC connections to
the drain

When a group of appliances are connected direct to the drain, under certain
circumstances a 110 mm stub stack may be used. Figure 9.10 shows a typical
ground-floor stub stack. Ventilation is required when the connection from
the invert of the drain to the highest connection of an appliance to the stack
exceeds 2 m, or the WC crown connection to the invert of the drain exceeds
1.3 m. Ventilation of a stub stack is via an air admittance valve.

Access cover or air
110 mm stub stack admittance valve

H1 = 2m max. (Scotland only)
H2 = 1.5 m max.
H3 = 1.3 m max. (England &
Wales only)

H2 H3 H1

d
d (single appliance) = 6m max.
d (group of appliances) = 12m max.
p Figure 9.10 The stub stack

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