Ariston Unvented Hot Water Storage Cylinders Instructions For Installation And Use Manual page 11

www.tradeplumbing.co.uk Call Sales On 08708034288
Temperature & pressure
relief valve
F . 2.9
IG
T 2. Sizing of copper discharge pipe "D2" for common temperature valve outlet sizes.
ABLE
Valve outlet size
G 1/2
G 3/4
G 1
www.tradeplumbing.co.uk Call Sales On 08708034288
connected. If unvented hot water storage systems are installed
where discharges from safety devices may not be apparent i.e. in
dwellings occupied by the blind, infirm or disabled people,
consideration should be given to the installation of an
electronically operated device to war n when discharge takes
place. Note: The discharge will consist of scalding water and
steam. Asphalt, roofing felt and non-metallic rainwater goods may
Metal discharge pipe (D1) from
temperature & pressure relief valve.
to tundish.
500mm Max.
300mm
Min.
Metal discharge pipe (D2) from tundish
with continuous fall. See Table 2 and worked
example.
Minimum size of Minimum size of
discharge pipe D1* discharge pipe D2*
from tundish
15mm
22mm
28mm
be damaged by such discharges.
WORKED EXAMPLE
The example below is for a G
discharge pipe (D2) having 4 no. elbows and length of 7m from the tundish to
the point of discharge.
From T 2;
ABLE
Maximum resistance allowed for a straight length of 22mm copper discharge
pipe (D2) from G
for 4 no. 22mm elbows at 0.8m each = 3.2m. Therefore the maximum permitted
length equates to: 5.8m. As 5.8m is less than the actual length of 7m therefore
Tundish
Maximum
resistance allowed,
expressed as a
length of pipe (i.e.
no elbow or bends)
22mm Up to 9m
28mm Up to 18m
35mm Up to 27m
28mm Up to 9m
35mm Up to 18m
42mm Up to 27m
35mm Up to 9m
42mm Up to 18m
54mm Up to 27m
1 / temperature & pressure relief valve with a
2
1 / temperature & pressure valve is 9m. Subtract the resistance
2
Discharge below
fixed grating.
(see page 10 for
alternative points
of discharge).
Fixed grating
Trapped gulley
Resistance created
by each elbow or
bend
0.8m
1.0m
1.4m
1.0m
1.4m
1.7m
1.4m
1.7m
2.3m
11