Low loss header
Application
Design rules for system hydraulics:
■ When balancing the low loss header, adjust the flow rate on the
equipment side to approx. 10 to 30 % below the flow rate on the
system side (reducing the return temperature).
■ The low loss header should be sized for the max. flow rate which
may occur in the overall system.
The low loss header separates the heat generator circuit (boiler cir-
cuit) from the downstream heating circuits.
A low loss header must be used if the max. flow rate of an individual
design is greater than the possible flow rate as shown on the rele-
vant "Residual head" graph.
For installation schemes in conjunction with low loss headers, see
"www.viessmann-schemes.com".
Heat generator circuit
The circulation pump in the Vitodens must be able to deliver the
required water volume against the (mostly low) pressure drop of the
heat generator circuit; the pressure drop of the low loss header is
negligible. The pump graphs are used to find the relevant residual
head for determining the internal pipe diameters, subject to the water
volume circulating in the heat generator circuit.
Heating circuit
The heating circuit pumps to be installed on site must be able to
deliver the water volume in the heating circuits against their pressure
drop. They must be sized accordingly.
Principle of operation
T1
T3
T2
T4
Vsecond.
Vprimary
V
primary
Heating water volume in the heat generator circuit (ap-
prox. 10 to 30 % less than V
secondary
)
V
secondary
Heating water volume, heating circuit
T
1
Flow temperature, heat generator circuit
T
2
Return temperature, heat generator circuit
T
3
Flow temperature, heating circuit
T
4
Return temperature, heating circuit
Q
primary
Amount of heat supplied by the heat generator
Q
secondary
Amount of heat transferred by the heating circuit
V
primary
< V
secondary
T
1
> T
3
T
2
≃
T
4
Q
primary
= Q
secondary
Note
Thermometers in the flow and return to the low loss header make
adjustments easier.
Low loss header (separate accessories)
See Vitodens installation accessories, page 93
Low loss header in conjunction with Divicon
Max. flow rate
in m
3
/h
Low loss header
– R ¾
4.5
– R 1
4.5
– R 1¼
7.5
Divicon heating circuit distributor
– R ¾
1.0
– R 1
1.5
– R 1¼
2.5
HR
HV
120
120
599
267
428
816
C
B
A
180
HR Heating return
HV Heating flow
A
Divicon heating circuit distributor
B
Manifold
C
Low loss header
HR
HV
120
120
790
267
428
816
120 180
180
HR Heating return
HV Heating flow
Design information
(cont.)
136
VIESMANN
VITODENS
8
5853906
Содержание Vitodens 200-W B2HE
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