Viessmann vitodens Technical Manual page 91

Testing the integral expansion vessel or the expansion vessel fitted to the mounting frame
Integral expansion vessel in Vitodens 200
Inlet pressure
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Blow-off pressure
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Capacity
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mounting frame with expansion vessel
(accessory for Vitodens 300)
Inlet pressure
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Blow-off pressure
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Capacity
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V = f ((V + V ) A + 2.4)
MAG A K f
V = Expansion vessel
MAG
volume
f = Expansion factor (= 2 for
expansion vessel)
V = System volume
A
V = Boiler water volume
K
Af = Heating water expansion factor
Calculating the heating system volume (approx. values)
1000
800
600
400
200
130
0
5 10 20
Output in kW
A Convectors
B Plate-type radiators
C Radiators
D Underfloor heating
VITODENS
Integral expansion vessel in Vitodens 333
0.75 bar Inlet pressure
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5 bar Blow-off pressure
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10 litres Capacity
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
0.75 bar
2.5 bar
11 litres
Example:
System: Vitodens 200
Boiler water volume 5 litres
Output 20 kW
Plate radiator
System volume approx. 130 litres
Heating system 70/65 ºC
Calculation:
Heating system 70/65 ºC: average water
temperature approx. 60 ºC
A = 0.0171
f
V = 2 · ((130 + 5)· 0.0171 + 2.4)
MAG
V = 9.42 litres
MAG
Result:
The integral expansion vessel
(10 litres capacity) is sufficiently
large for this system.
D
C
B
A
30 40
3.3 Expansion vessels
When making the water connections,
0.75 bar check that the size of the expansion
2.5 bar vessel matches the system conditions.
12 litres
The following steps will enable you to
make a rough check.
Note
If the integral expansion vessel or the
expansion vessel in the mounting frame
is insufficient, connect an adequately
sized expansion vessel to the expansion
vessel connector on Vitodens.
Calculating expansion factor A
Average water temp.
[ºC]
50
60
70
50
3
f
Expansion factor
A
f
0.0121
0.0171
0.0228
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