Viessmann VITODENS 200-W Type B2HA Technical Manual page 43

Installation accessories
² = µ · c · ΔT c = 1.163
kg · K
11600 W · kg · K
²
´ = =
c · ΔT 1.163 Wh · (75-60) K
Select the smallest possible mixer within the application limit with the
value ´.
Circulation pump curves and pressure drop on the heating
water side
The residual pump head results from the differential between the
selected pump curve and the pressure drop curve of the respective
heating circuit distributor or further components (pipe assembly, dis-
tributor, etc.).
The following pump graphs show the pressure drop curves of the dif-
ferent Divicon heating circuit distributors.
Maximum flow rate for Divicon:
■ With R ¾ = 1.0 m
3 /h
■ With R 1 = 1.5 m
3 /h
■ With R 1¼ = 2.5 m
3 /h
Example:
3
Flow rate ´ = 0.665 m /h
Selected:
■ Divicon with mixer R ¾
■ Wilo Yonos PARA 25/6 circulation pump, variable differential pres-
sure operating mode and set to maximum delivery head
■ Pump rate 0.7 m 3
/h
Head of the relevant pump
curve:
Divicon pressure drop:
Residual head:
Note
For further components (pipe assembly, distributor, etc.) determine
the pressure drop and deduct it from the residual head.
Differential pressure-dependent heating circuit pumps
According to the [German] Energy Saving Ordinance (EnEV), circu-
lation pumps in central heating systems must be sized in accordance
with current technical rules.
Ecodesign Directive 2009/125/EC requires high efficiency circulation
pumps to be used throughout Europe from 1 January 2013, if the
pumps are not installed in the heat generator.
Design information
The use of differential pressure-dependent heating circuit pumps
requires heating circuits with variable pump rates. These include e.g.
single and twin line heating systems with thermostatic valves and
underfloor heating systems with thermostatic or zone valves.
VITODENS 200-W
(cont.)
Wh
´ (1 kg ≈ 1 dm³)
µ
kg m³
= 665 0.665
h h
48 kPa
3.5 kPa
48 kPa – 3.5 kPa = 44.5 kPa.
Result of this example: Divicon with mixer-3 (R ¾)
Wilo Yonos PARA 25/6
■ Particularly power saving, high efficiency circulation pump
■ Energy efficiency index EEI ≤ 0.20
Operating mode: Constant differential pressure
700 70
600 60
500
50
400
40
300
30
200 20
100 10 B
A
0 0
0.5 1.0 1.5 2.0 2.5
0
Flow rate in m³/h
A Divicon R ¾ with mixer
B Divicon R 1 with mixer
C Divicon R ¾ and R 1 without mixer
Operating mode: Variable differential pressure
700 70
600 60
500 50
400
40
300 30
200 20
100
10
B
A
0 0
0
0.5 1.0 1.5 2.0 2.5
Flow rate in m³/h
A Divicon R ¾ with mixer
B Divicon R 1 with mixer
C Divicon R ¾ and R 1 without mixer
C
3.0 3.5
C
3.0 3.5
VIESMANN
2
43