Ariston EP 10 UR 2 KW Podręcznik - Strona 10
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Table 2
Sizing of copper discharge pipe "D2" for common temperature valve outlets.
Valve outlet size
G 1/2
G 3/4
G 1
8
Minimum size of
Minimum size of
discharge pipe D1*
discharge pipe D2*
15 mm
22 mm
28 mm
Worked example
The example below is for a G 1/2" temperature & pressure relief valve with
a discharge pipe (D2) having 4 no. elbows and length of 7 m from the
tundish to the point of discharge.
From Table 2
Maximum resistance allowed for a straight length of 22 mm copper
discharge pipe (D2) from G 1/2" T & P valve is 9 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.
As 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
G 1/2" T & P valve equates to: 18 m.
Subtract the resistance for 4 no. 28 mm elbow at 1.0 m each = 4 m.
Therefore the maximum permitted length equates to: 14 m
As the actual length is 7 m, a 28 mm (D2) copper pipe will be satisfactory.
d) ELECTRICAL
WARNING:
The electrical installation must be in line with the current I.E.E. wiring
regulations.
A mains supply of 240 VAC 3 kW (13 amps) is required (Fig. 5 & 6)
Heat resisting cable, round 3 core 1.5 mm (to BS 6141 table 8) should be
used to connect to the electrical supply through either:
- a 13 amp socket to BS 1363; or
- a double pole fused isolating switch with a contact separation of 3 mm
minimum on each pole.
The cable enters the terminal compartment through a tube embedded in
Maximum
resistance allowed,
from tundish
expressed as a
length of pipe (i.e.
no elbow or bends)
22 mm
Up to 9 m
28 mm
Up to 18 m
35 mm
Up to 27 m
28 mm
Up to 9 m
35 mm
Up to 18 m
42 mm
Up to 27 m
35 mm
Up to 9 m
42 mm
Up to 18 m
54 mm
Up to 27 m
The appliance must be earthed
Resistance created
by each elbow or
bend
0.8 m
1.0 m
1.4 m
1.0 m
1.4 m
1.7 m
1.4 m
1.7 m
2.3 m