Supplied By www.heating spares.co Tel. 0161 620 6677
16
B) Where fitting of a make up vessel would be
difficult, re pressurisation of the system can be
done. See section on FILLING. If the capacity
of the central heating system should exceed
110 Litres, an additional vessel should be
installed on the return to the combination boiler
from the heating system (Fig. 7). Guidance on
vessel sizing is given in (Table 3).
Reference should be made to British Gas
Publications, «Material and Installation
Specifications for Domestic Central Heating
and Hot Water». Draining taps should be
at least 1/2” in BSP nominal size and be in
accordance with BS 2879.
4.8.9
Installation to an existing central heating
system
The combination boiler is designed to operate
on a sealed system only. Therefore if the
existing system is of the open water type it will
have to be modified to comply with BS 5376
Part 2.
Before installing a new combination boiler to
an existing system, flush out the old system
with a recommended descaling agent.
If the boiler is installed in an existing system
any unsuitable additives
MUST
be removed
by thorough cleaning.
BS 7593:1992 details the steps necessary to
clean domestic central heating system. Also
check pipework and renew any corroded
pipework or fittings. Valve glands must be
repacked or replaced wherever necessary
and any defective controls exchanged.
WATER TREATMENT
This boiler has a stainless steel heat
exchanger Ravenheat recommended only the
use of FERNOX- COPAL or SENTINEL X100
water treatment products, which must be
used in accordance with the manufacturers
instructions. For further information contact:
Fernox Manufacturing Co. Ltd.
Tel 01799 550811
Sentinel Division Betz Dearborn Ltd.
Tel. (0151) 424 5351
Safety
valve setting (bar)
3.0
Vessel charge
pressure (bar)
0.5
1.0
1.5
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
50
75
100
125
150
175
200
225
250
275
300
325
350
375
400
425
450
475
500
2.1
4.2
6.3
8.3
10.4
12.5
14.6
1 6 . 7
1 8 . 7
2 0 . 8
2 2 . 9
25.0
2 7 . 0
2 9 . 1
31 .2
33.3
3 5 . 4
37.5
39.6
41.6
3.5
7.0
10.5
14.0
17.5
21.0
24.5
28.0
31 .5
35.0
38.5
42.0
45.5
49.0
52.5
56.0
59.5
63.0
66.5
7 0 . 0
6.5
12.9
19.4
25.9
32.4
38.8
45.3
51 .8
58.3
64.7
71 .2
7 7 . 7
84.1
90.6
97 .1
103.6
110.1
116.5
123.0
125.9
13.7
27.5
41.3
55.1
68.9
82.6
96.4
110.2
124.0
137.7
151 .5
165.3
179 .1
192.8
206.6
220.4
239.2
247.9
261 .7
275.5
2.7
5.4
8.2
10.9
13.6
16.3
19.1
21.8
24.5
27.2
30.0
32.7
35.7
38 .1
40.9
43.6
46.3
49.0
51 .8
54.5
4.7
9.5
14.2
19.0
23.7
28.5
33.2
38.0
42.7
47.5
52..2
57.0
61 .7
66.5
71 .2
7 6 . 0
80.7
85.5
90.2
95.0
10.3
20.6
30.9
41.2
51.5
61.8
72.1
82.4
92.7
103.0
113.3
123.6
133.9
144.2
154.5
164.8
175.1
185.4
195.7
206.0
3.9
7.8
11.7
15.6
19.5
23.4
27 .3
31.2
35 .1
39.0
42.9
46.8
50.7
54.6
58.5
62.4
66.3
70.2
74.1
7 8 . 0
8.3
16.5
24.8
33.1
41.3
49.6
57.9
66.2
74.5
82.7
91.0
99.3
107.6
115.8
124.1
132.4
140.7
148.9
157.2
1 6 5 . 5
For system volumes
other than those given
above, multiply the
system volume by
the factor across
0.0833
0.140
0.259
0.551
0 .109
0.190
0.412
0.156
0.331
SIZING OF ADDITIONAL EXPANSION VESSEL: TABLE 3
Deduct from the value given in the table the 7 litre vessel supplied.
Note: This pressure can be increased up to 1.5 bar to suit high static head situations, see item 10, other appliance components in the
SERVICING INSTRUCTIONS.
