Glow-worm Clearly Solar Cylinders - Manual (Page 18)

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INSTALLATION
9.3.2 Discharge requirements (g3 building
regulations)
METAL DISCHARGE PIPE FROM
TEMPERATURE RELIEF VALVE
TO TUNDISH
METAL DISCHARGE PIPE
FROM TUNDISH WITH
CONTINUOUS FALL
TUNDISH
DISCHARGE
BELOW
FIXED
GRATING
FIXED
GRATING
TRAPPED GULLY
SAFETY DEVICE
(E.G. TEMPERATURE
RELIEF VALVE
VENTIL)
600 MM
300 MM
MINIMUM
The discharge connections of the temperature/pressure relief
valve and the expansion relief valve must be connected with
the supplied tundish via 15 mm copper piping. The tundish
should be attached so that it is vertical, as near to the cylinder
as possible, and not more than 600 mm from the connection
of the temperature/ pressure relief valve. It must be mounted
in the same room as the cylinder at a sufficient distance from
the electrical components. The discharge pipes from the
temperature/pressure relief valve and expansion relief valve can
be joined above the tundish using a T-piece.
The discharge pipe from the 22 mm connection of the drain
funnel must be laid using copper piping with a diameter of at
least 22 mm to a safe and visible discharge point.
There must be a vertical section of pipe at least 300 mm long
beneath the tundish before any bends or elbows in the pipework.
If the total resistance of the discharge pipe exceeds the values
specified in table below, you must increase the diameter of the
piping. When installing the discharge piping, you must observe
Directive G3 (section 2.5).
9.3.3 sizing of copper discharge pipe for g1/2
temperature and pressure relief valve outlet size
Minimum diameter of
discharge pipe from
tundish
Maximum
permissable total
resistance, expressed
as straight pipe
length (without
elbows or bends)
Resistance due to
each elbow or bend
22 mm Up to 9 m 0.8 m
28 mm Up to 18 m 1.0 m
35 mm Up to 27 m 1.4 m
Worked example
The example below is for a G1/2 temperature relief valve with
a discharge pipe having 4 No. 22 mm elbows and length of 7 m
from the tundish to the point of discharge.
From Sizing Table:
Maximum resistance allowed for a straight length of 22 mm
copper discharge pipe from a G1/2 temperature relief valve is:
9.0 m.
Subtract the resistance for 4 No. 22 mm elbows at 0.8 m each =
3.2 m.
Therefore the maximum permitted length equates to: 5.8 m,
which is less than the actual length of 7 m therefore calculate the
next largest size.
Maximum resistance allowed for a straight length of 28 mm pipe
from a G1/2 temperature relief valve is: 18 m.
Subtract the resistance of 4 No. 28 mm elbows at 1.0 m each =
4.0 m.
Therefore the maximum permitted length equates to: 14 m.
As the actual length is 7 m, a 28 mm copper pipe will be
satisfactory.
A suitable place for the end of the discharge pipe is, for
example, beneath a fixed grille above the odour seal in a gully
with a siphon. Low discharge pipes, for example up to 100 mm
above external surfaces such as car and other parking spaces,
grasslands etc. can be used provided that they are secured by a
wire fence or something similar to prevent children from coming
into contact with the waste water and as long as the system is
not visible. You must not install any valves or stop cocks in the
discharge pipe.
• Make sure that the discharge pipe from the tundish to the
drain has a constant downward incline of at least 1:200. The
discharge pipe from the pressure relief valve of the Glow-worm
gas-fired boiler can be connected to the horizontal discharge
pipe of the cylinder behind the tundish using a T-piece.