Viessmann VITOCROSSAL 200 Type CM2 Technical Manual page 16

Installation accessories
Residual head
Residual head of the heating circuits
Deduct the pressure drop of the mixer and the boiler circuit (boiler,
pipework, flow distributor and return collector) from the pump head.
The total water volume of all heating circuits should be taken into con-
sideration in the boiler circuit.
Boiler circuit pressure drop
(Boiler + pipework + flow distributor and return collector + heating cir-
cuit connection without mixer)
100 10
50 5
40 4
30 3
20 2
15 1.5
10 1
5 0.5
4 0.4
3 0.3
2 0.2
1 0.1
1
Flow rate in m³/h
A DN 65: Vitocrossal 300, 87 to 142 kW,
B DN 65: Vitocrossal 300, 187 and 248 kW,
C DN 80: Vitocrossal 300, 314 kW,
Example for calculating the residual head
Heating system with:
– Divicon heating circuit distributor DN 80
– Heating cir- 1 heating circuit connection DN 25 without mixer,
7
cuit 1:
– Heating cir- 1 heating circuit connection DN 32 with mixer,
cuit 2:
– Heating cir- 1 heating circuit connection DN 50 with mixer,
cuit 3:
Boiler circuit pressure drop
Boiler + pipe connections + flow distributor and return collector + heat-
ing circuit connection (except mixer) (see diagram) = 30 mbar
(3 kPa)
Sum of the boiler circuit pressure drop and heating circuit connection pressure drop
Heating circuit 1: 30 mbar (3 kPa)
Heating circuit 2: 30 mbar + 18 mbar = 48 mbar (4.8 kPa)
VIESMANN
16
(cont.)
A B
2 3 4 5 10 15 20
Mixer pressure drop
50
500
200 20
10
100
C
50 5
20 2
10 1
5 0.5
2 0.2
1 0.1
0.1
Throughput in m³/h
A DN 25
B DN 32
C DN 40
D DN 50
Note
For the pressure drop of the pipe connections between the boiler and
distributor, 6 bends (90°) and 5 m pipe length are factored in. If con-
siderably different lengths and shapes are used on-site, calculate and
factor in the additional pressure drop levels.
heating output 35 kW,
heating output 60 kW,
heating output 150 kW,
Mixer pressure drop
(see diagram)
Mixer
Pressure drop
A
5
0.2 0.5 1 2
Total flow rate 10.5 m
DN
mbar
kPa
Gas condensing boilers
B C D
20
10
3
flow rate 1.5 m /h
3
flow rate 2.5 m /h
3
flow rate 6.5 m /h
3 /h
32 50
18 22
1.8 2.2