Hydraulic Specifi Cations; Expansion Vessel - Biasi Activ A 18S User Manual And Installation Instructions

4.3 Hydraulic specifi cations
The hydraulic specifi cations represents the
pressure (available head for the central
heating system) as a function of the fl ow
rate.
Model Activ A 18S
Pression (bar)
0,60
0,54
0,48
0,42
0,36
0,30
0,24
0,18
0,12
0,06
0,00
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
Fig. 4.3
Models Activ A 25S - Activ A 30S
Pression (bar)
0,60
0,54
0,48
0,42
0,36
0,30
0,24
0,18
0,12
0,06
0,00
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
Fig. 4.4
The boiler load loss has already been re-
moved.
Flow rate with closed thermostatic
valves
The boiler is equipped with an automatic
by-pass, which protects the condensing pri-
mary exchanger.
In case of excessive reduction or total stop-
ping of water circulation in the heating plant
TECHNICAL INFORMATION
Flow (l/h)
Flow (l/h)
due to the closing of thermostatic valves or
circuit elements valves, by-pass ensures a
minimum water circulation inside the con-
densing primary exchanger.
The by-pass is calibrated to a differential
pressure of about 0.3-0.4 bar.
4.4

Expansion vessel

Note: this boiler is designed for opera-
tion only in a sealed central heating sys-
tem.
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
additional 1m.
Total capacity
Pre-load pressure
Useful capacity
Maximum volume of water in the
system *
Fig. 4.5
* Where conditions are:
• Average maximum temperature of the sys-
tem is 85 °C
• Initial temperature when fi lling up the sys-
tem is 10 °C.
For systems with volumes great-
er then the one indicated in the
above table, an additional expan-
sion vessel must be provided.
l 7,0
kPa 100
bar 1,0
l 3,5
l 109
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