7
Fixed grating
Discharge below
fixed grating
(Building Regulation
G3 section 3.9d gives
alternative points
of discharge)
Trapped
gully
Discharge pipe (D2) from tundish,
with continuous fall. See Building
Regulation G3 section 3.9d i-iv,
Table 4 and worked example
300mm
minimum
500mm maximum
Metal discharge pipe (D1) from
Temperature relief valve to tundish
Tundish
Safety device
(e.g. Temperature
relief valve)
Valve outlet size
Minimum size of
discharge pipe
D1
Minimum size of
discharge pipe
D2 from tundish
Maximum
resistance
allow ed,
expre ssed as a
length of straight
pipe (I.e. no
elbow s or bends)
Resistance
created by each
elbow or bend
G1/2
15mm
22mm
28mm
35mm
up to 9m
up to 18m
up to 27m
0.8m
1.0m
1.4m
G3/4
22mm
28mm
35mm
42mm
up to 9m
up to 18m
up to 27m
1.0m
1.4m
1.7m
G1
28mm
35mm
42mm
54mm
up to 9m
up to 18m
up to 27m
1.4m
1.7m
2.3m
Table 4 Sizing of copper discharge pipe (D2) for common temperature relief valve outlet sizes
FIG. 4 Typical discharge pipe arrangement (extract from Building Regulation G3 Guidance
section 3.9)
3.9 WARNINGS
•
Under no circumstances should the factory fitted
Temperature/Pressure Relief Valve be removed other
than by authorised personnel. To do so will invalidate
any guarantee or claim.
•
The Cold Water Combination Valve must be fitted
to the mains water supply to the Heatstore HSU unit.
•
No control or safety valves should be tampered
with.
•
The discharge pipe should not be blocked or used
for any other purpose.
•
The tundish should not be located adjacent to any
electrical components.
