andrews Flexistor 400 Installation Manual page 20

Notes:
1) Discharge pipe-work D2 can now be a plastic pipe but only pipes that have been tested to a
minimum 110°C must be used.
2) Discharge pipe D2 can now be plumbed in the soil stack but only soil stacks that can handle
temperatures of 99°C or greater should be used.
VALVE OUTLET
SIZE
G 1/2
G 3/4
G 1
Table 10 Sizing of copper discharge pipe "D2" for common T&P Relief Valve sizes.
Safety device
(e.g. Temperature
relief valve)
600mm maximum
Discharge pipe (D2) from tundish,
with continuous fall. See Building
Table 1 and worked example
:
Figure 10 Typical discharge pipe arrangement (Extract from Building Regulations G3
Guidance section 3.5 to 3.63)
20
MINIMUM SIZE OF
DISCHARGE PIPE D1
15mm
22mm
28mm
Metal discharge pipe (D1) from
Temperature relief valve to tundish
300mm
minimum
Regulation G3 section 3.56,
MINIMUM SIZE OF
MAXIMUM RESISTANCE
DISCHARGE PIPE D2
ALLOWED, EXPRESSED
FROM TUNDISH
AS A LENGTH OF
STRAIGHT PIPE (I.E. NO
ELBOWS OR BENDS
22mm UP TO 9m
28mm UP TO 18m
35mm UP TO 27m
28mm UP TO 9m
35mm UP TO 18m
UP TO 27m
42mm
35mm UP TO 9m
42mm UP TO 18m
54mm UP TO 27m
Tundish
RESISTANCE CREATED BY
EACH ELBOW OR BEND
0.8m
1.0m
1.4m
1.0m
1.4m
1.7m
1.4m
1.7m
2.3m
Discharge below
fixed grating
(Building Regulation
G3 section 3.61 gives
alternative points
of discharge)
Fixed grating
Trapped
gully