Viessmann VITODENS 200-W Technical Manual page 22

Installation accessories
C Divicon R 1¼ with mixer
D Divicon R ¾, R 1 and R 1¼ without mixer
Heating circuit pumps regulated by differential pressure
According to the [German] Energy Savings Order (EnEV), circulation
pumps in central heating systems must be sized in accordance with
current technical rules. Circulation pumps in central heating systems
with rated output higher than 25 kW should be equipped and designed
in such a way that the power consumption will be automatically
matched to the operational (capacity) requirements in at least 3 stages,
if no safety concerns relating to the boiler make demands to the con-
trary.
2
Wilo Stratos Para 25/1-7
■ Very economical HE pump (in accordance with Energy Label A)
Operating mode: Constant differential pressure
700 70
600 60
500 50
400 40
300 30
200 20
100 10
0 0
0 0.5
Pump rate in m³/h
A Divicon R ¾ with mixer
B Divicon R 1 with mixer
VIESMANN
22
(cont.)
B C
A
1.0 1.5 2.0
In addition to the EnEV regulations, the use of regulated pumps is also
recommended for smaller capacities.
Design information
The use of differential pressure regulated heating circuit pumps
requires heating circuits with variable flow rate, e.g. single line and
twin-line systems with thermostatic valves, underfloor heating with
thermostatic or zone valves.
D
2.5 3.0 3.5 4.0
C Divicon R 1¼ with mixer
D Divicon R ¾, R 1 and R 1¼ without mixer
VITODENS 200-W