8
Fig. 4b
c. Termination into a hopper
At high level, discharge onto a roof is acceptable providing the roof is capable of withstanding high temperatures and
there is a distance of 3 m from any plastic guttering systems that would collect such discharge.
Note:
The discharge will consist of scalding water and steam. Asphalt, roofing felt and non-metallic rainwater goods may
be damaged by such discharges.
b. High level termination
D1
D2
300 mm
minimum
Tundish
Type 'A'
air gap
End of pipe to be
clearly visible
300 mm
minimum
Tundish
500 mm max.
Metal discharge pipe (D2) from
tundish with continuous fall
Metal discharge pipe (D1)
from relief valve to tundish
Solar cylinder
temperature/pressure
relief valve
300 mm
minimum
100 mm max.
70 mm min.
Gulley if
available
Pipe close to wall to
allow water to fan out
safely
Ground level
D2
D1
a. Low level termination
To expansion
relief valve
Worked example:-
The example below is for a G½ temperature relief valve with a discharge pipe (D2)
having four elbows and a length of 7 m from the tundish to the point of discharge.
From the table on page 6:-
Maximum resistance allowed for a straight length of 22 mm copper discharge pipe
(D2) from a G½ temperature relief valve is 9 m.
Subtract the resistance for four 22 mm elbows of 0.8 m each = 3.2 m.
Therefore the maximum permitted length equates to 9 - 3.2 = 5.8 m
5.8 m 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 (D2) from a G½
temperature relief valve equates to 18 m.
Subtract the resistance for four 28 mm elbows at 1.0 m each = 4 m.
Therefore the maximum permitted length equates to 18 - 4 = 14 m
As the actual length is 7 m, a 28 mm (D2) copper pipe will be satisfactory.
Alpha SolarSmart 90 - General Information
Given below are suggested methods of terminating the discharge pipe safely.
Where a single pipe serves a number of discharges, such as in blocks of flats, the number served should be limited to not
more than 6 systems so that any installation can be traced reasonably easily. The single common discharge pipe should
be at least one pipe size larger than the largest individual discharge pipe to be connected.
If the system is installed where discharges from safety devices may not be apparent, i.e. in dwellings occupied by blind, infirm or disabled
people, consideration should be given to the installation of an electronically operated device to warn when discharge takes place.
Fig. 4a
