Jet 120i Installation & Servicing Instructions Manual page 10

MINIMUM
VALVE
SIZE OF
OUTLET
DISCHARGE
SIZE
PIPE D1
G 1/2 15mm
G 3/4 22mm
G1 28mm
Table 03: Sizing of copper discharge pipe (D2) for common temperature relief valve outlet sizes
NOTE: The table below is based on copper tube. Plastic pipes may be of different bore and resistance. Sizes
and maximum lengths of plastic should be calculated using data prepared for the type of pipe being used.
Safety device
(e.g. Temperature
relief valve)
Discharge pipe (D2) from tundish,
with continuous fall. See Building
Table 1 and worked example
Figure 04: Typical discharge pipe arrangement (Extract from building regulation G3 guidance section 5.50)
10
MINIMUM SIZE OF
DISCHARGE PIPR
D2 FROM TUNDISH
22mm
28mm
35mm
28mm
35mm
42mm
35mm
42mm
54mm
Metal discharge pipe (D1) from
Temperature relief valve to tundish
600mm maximum
300mm
minimum
Regulation G3 section 3.56,
MAXIMUM RESISTANCE
ALLOWED, EXPRESSED
AS A LENGTH OF
STRAIGHT PIPE
ELBOWS OR BENDS)
UP TO 9M
UP TO 18M
UP TO 27M
UP TO 9M
UP TO 18M
UP TO 27M
UP TO 9M
UP TO 18M
UP TO 27M
Tundish
RESISTANCE
CREATED BY
EACH ELBOW
(I.E. NO
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