We recommend use of a Ravenheat
be at least l/2" in BSP nominal size and be
Filling Loop
designed for this method of
in accordance with BS 2879.
filling the system. Available from your
supplier.
4.8.9
lnstallation to an existing central heating
system
PROVISIONS FOR MAKE UP WATER
The combination boiler is designed to oper-
(Fig. 7)
ate on a sealed system only. Therefore if
Provision can be made for replacing water
loss from the system either.
the existing system is of the open water
type it will have to be modified to comply
A) from a manually filled made up bottle
with BS 5376 Part 2.
with a readily visible water level. The bottle
Before installing a new combination boil-
should be mounted at least 150 mm (6 in)
er to an existing system flush out the old
above the highest point of the system and
system with a recommended descaling
be connected through a non return valve to
agent.
the return side of the heating system.
Also check pipework and renew any corrod-
B) Where fitting a make up vessel would be
ed pipework or fittings, Valve glands must
difficult re pressurisation of the system can
be repacked or replaced wherever neces-
be done. See section on FILLING.
sary and any defective controls exchanged.
If the capacity of the central heating system
should exceed 110 litres,
an additional
4.8.10
Hard water areas
vessel may be installed if required on the
If the area of installation is recognized as a
return to the combination boiler from the
hard water, it is recommended that a suit-
heating system (Fig. 7). Guidance on ves-
able water treatment device is installed in
sel sizing is given in (Table 5).
the mains.
Reference should be made to British Gas
The water hardness can be determined by
Publications << Material and Installation
using the standard test paper or by refer-
Specifications for Domestic Central Heat-
ring to local water authority.
ing and Hot Water >>. Draining taps should
SIZING OF ADDITIONAL EXPANSION VESSELS:TABLE 5
Safety
valve setting (bar)
3.0
Vessel charge
pressure (bar)
0.5
1.0
Initial system
pressure (bar)
0.5
1.0
1.5
2.0
1.0
1.5
2.0
1.5
2.0
Total water
content Of System
EXPANSION VESSEL VOLUME (LITRES)
Litres
25
2.1
3.5
6.5
13.7
2.7
4.7
10.3
3.9
8.3
50
4.2
7.0
12.9
27.5
5.4
9.5
20.6
7.8
16.5
75
6.3
10.5
19.4
41.3
8.2
14.2
30.9
11.7
24.8
100
8.3
14.0
25.9
55.1
10.9
19.0
41.2
15.6
33.1
125
10.4
17.5
32.4
68.9
13.6
23.7
51.5
19.5
41.3
150
12.5
21.0
38.8
82.6
16.3
28.5
61.8
23.4
49.6
175
14.6
24.5
45.3
96.4
19.1
33.2
72.1
27.3
57.9
2 0 0
16.7
28.0
51.8
110.2
21.8
38.0
82.4
31.2
66.2
2 2 5
18.7
31.5
58.3
124.0
24.5
42.7
92.7
35.1
74.5
2 5 0
20.8
35.0
64.7
137.7
27.2
47.5
103.0
39.0
82.7
2 7 5
22.9
38.5
71.2
151.5
30.0
52.2
113.3
42.9
91.0
3 0 0
25.0
42.0
77.7
165.3
32.7
57.0
123.6
46.8
99.3
3 2 5
27.0
45.5
84.1
179.1
35.7
61.7
133.9
50.7
107.6
3 5 0
29.1
49.0
90.6
192.8
38.1
66.5
144.2
54.6
115.8
3 7 5
31.2
52.5
97.1
206.6
40.9
71.2
154.5
58.5
124.1
4 0 0
33.3
56.0
103.6
220.4
43.6
76.0
164.8
62.4
132.4
4 2 5
35.4
59.5
110.1
239.2
46.3
80.7
175.1
66.3
140.7
4 5 0
37.5
63.0
116.5
247.9
4 9 . 0
85.5
185.4
70.2
148.9
4 7 5
39.6
66.5
123.0
261.7
51.8
90.2
195.7
74.1
157.2
500
41.6
70.0
125.9
275.6
54.5
95.0
206.0
78.0
165.5
For system volumes
other than those given
above, multiply the
0.0833
0.140
0.259
0.551
0 . 1 0 9
0.190
0.412
0.156
0.331
system volume by
the factor across
16
Summary of Contents for RSF 84E
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Page 55: ...Chartists Way Morley Leeds LS27 9ET Telephone 0113 252 7007 Tfax 0113 238 0229...
