MEGAFLO Commercial 1000, Product Manual

Page: 20 / 40

Unvented Hot Water Cylinder
20
INST
ALLA
TION AND
COMMISSIONING (2)
600mm maximum
300mm
minimum
Safety device
(e.g. Temperature
relief valve)
Metal discharge pipe (D1) from
Temperature relief valve to tundish
Tundish
Discharge below
fixed grating
(Building Regulation
G3 section 3.61 gives
alternative points
of discharge)
Fixed grating
Trapped
gully
Discharge pipe (D2) from tundish,
with continuous fall. See Building
Regulation G3 section 3.56,
Table 1 and worked example
Figure 11
:
Typical discharge pipe arrangement (Extract from Building Regulations G3
Guidance section 3.5 to 3.63)
VALVE OUTLET
SIZE
MINIMUM SIZE OF
DISCHARGE PIPE D1 MINIMUM SIZE OF
DISCHARGE PIPE D2
FROM TUNDISH
MAXIMUM RESISTANCE
ALLOWED, EXPRESSED
AS A LENGTH OF
STRAIGHT PIPE (I.E. NO
ELBOWS OR BENDS
RESISTANCE CREATED BY
EACH ELBOW OR BEND
G 1/2 15mm 22mm
28mm
35mm UP TO 9m
UP TO 18m
UP TO 27m 0.8m
1.0m
1.4m
G 3/4 22mm 28mm
35mm
42mm UP TO 9m
UP TO 18m
UP TO 27m 1.0m
1.4m
1.7m
G 1 28mm 35mm
42mm
54mm UP TO 9m
UP TO 18m
UP TO 27m 1.4m
1.7m
2.3m
Table 15 Sizing of copper discharge pipe “D2” for common T&P Relief Valve sizes.
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.