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4.5
Hydraulic specifications
The hydraulic specifications in Fig. 4.3 rep-
resent the pressure (available head for the
central heating system) as a function of the
flow rate.
The load loss due to the boiler has already
been subtracted.
kPa bar
0.6
60
50
0.5
40
0.4
30
0.3
20
0.2
10
0.1
0
0.0
0
200
400
Fig. 4.3
Output with thermostat cocks shut off
The boiler is equipped with an automatic by-
pass valve (38on page 17), which protects
the condensing primary exchanger.
In case of excessive reduction or total
blockage of water circulation in the cen-
tral heating system owing to closure of the
thermostatic valves or system component
cocks, the by-pass valve ensures a mini-
mum flow of water through the primary heat
exchanger.
4.6
Expansion vessel
Note: this boiler is designed for operation
only in a sealed central heating system
The height difference between the pressure
relief valve and the highest point in the sys-
tem may be 10m at most.
For greater differences, increase the pre-
load pressure in the expansion vessel and
the system, when cold, by 0.1 bar for each
- 24 -
TECHNICAL INFORMATION
600
800
1000 1200 1400
l/h
additional 1 m.
Capacity
Pre-load pressure
Maximum volume of water in the
system *
Fig. 4.4
* Where conditions are:
• Average maximum temperature of the sys-
tem is 85 °C
• Initial temperature when filling up the sys-
tem is 10 °C
For systems with volumes great-
er than 124 l, an additional ex-
pansion vessel must be provid-
ed.
l
8,0
kPa
100
bar
1,0
l
124
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