Nimbus Compact M NET R32 Installation Manual UK

Hydraulic connections
– discharges at high level: e.g. into a metal hopper and
metal downpipe with the end of the discharge pipe
clearly visible or onto a roof capable of withstanding
high-temperature discharges of water and 3 m from
any plastic guttering system that would collect such
discharges.
– The discharge would consist of high-temperature water
and steam. Asphalt, roofing felt and non-metallic rainwater
goods may be damaged by such discharges.
Discharge pipe (D2) characteristics
– The discharge pipe (D2) should be made of metal or
other material with proven capacity to safely withstand
the high temperatures of the water discharged (above
95°), and be clearly and permanently marked to identify
the product and its performance rating.
– The discharge pipe (D2) should be at least one pipe-size
larger than the nominal outlet size of the safety device,
unless its total equivalent hydraulic resistance exceeds
that of a 9 m-long straight pipe, i.e. for discharge pipes
between 9 m and 18 m long, the equivalent resistance
length should be at least two sizes larger than the nominal
outlet size of the safety device; between 18 m and
27 m, it should be at least 3 sizes larger, and so forth;
bends must be taken into account when calculating
the flow resistance.
Typical discharge pipe arrangement
1
600 mm
Maximum
2
300 mm
Minimum
4
3
5
6
Fig. 48
1 Safety device (e.g. temperature relief valve)
2 Metal discharge pipe (D1) from the temperature relief
valve to the tundish
3 Tundish
4 Discharge pipe (D2) from the tundish, with continuous
fall. (refer to “Connection of the discharge pipe (D2) to the
tundish” in paragraph Safety device connection, the table
below and the worked example)
5 Fixed grating
6 Trapped gully
Discharge below fixed grating (see figure above).
Sizing of copper discharge pipe (D2) for common temperature
relief valve outlet sizes:
Valve outlet size G1/2
Minimum size of discharge pipe D1
15 mm
Minimum size of discharge pipe D2 from 22 mm
tundish
28 mm
35 mm
Maximum allowed resistance, expressed
as the length of a straight pipe (i.e without
elbows or bends)
Resistance generated by each elbow or bend
Up to 9 m
Up to 18 m
Up to 27 m
0.8 m
1.0 m
1.4 m
Worked example
The example below is for a G½ temperature relief valve with a
discharge pipe (D2) having 4 x 22 mm elbows and a 7 m length
from the tundish to the point of discharge.
– From the above table, the maximum allowed resistance
for a straight length of 22 mm copper discharge pipe
(D2) from a G½ temperature relief valve is: 9.0 m;
– Subtract the resistance for 4 x 22 mm elbows at 0.8 m
each = 3.2 m;
– Therefore, the maximum allowed length amounts to 5.8
m, which is less than the current length of 7 m, so calculate
the next largest size;
– Maximum allowed resistance for a straight length of 28
mm copper discharge pipe (D2) from a G½ temperature
relief valve is: 18 m;
– Subtract the resistance for 4 x 28 mm elbows at 1.0 m
each = 4 m;
– Therefore, the maximum allowed length amounts to: 14 m;
– Since the current length is 7 m, a 28 mm (D2) copper
pipe will do.
a
The outlet from the temperature and pressure
relief valve and expansion relief valve must not
be used for any other purpose. The temperature
and pressure relief valve must not be removed
under any circumstances.
4.2.5 Hydraulic connections
Description
Connection
Type
Connection
Size
T&P discharge Male G 1/2
Safety inlet assembly:
Safety valve Compression D 15
Exp. vessel inlet Famale 3/4”
inlet
Cold mains water Compression 22 mm
Cylinder outlet
Compression 23 mm
Expansion vessel Male 3/4 Gas
a
The installer must verify and provide evidence of
conformity with respect to the following regulations:
– The Building Regulations 2010 (S.I. 2010 No.
2214), as amended;
– The Water Supply (Water Fittings) Regulations
1999 (S.I. 1999 No. 1148), as amended.
30 / EN