Viessmann VITODENSd 100-W Technical Data Manual page 18

Installation
Accessories
Accessories for the Vitodens 100-W
Neutralization Unit for Single-Boiler Applications
with neutralizing granulate for Vitodens 100-W, WB1B 26, 35
Part No. 7134 231
Low-Loss Header
- Type 80/50, Part No. 7134 791
[max. flow rate 17.6 GPM (4 m3/h)]
- Type 120/80, Part No. 7134 792
[max. flow rate 35.2 GPM (8 m3/h)]
A low-loss header offers additional benefits
not provided by a pair of closely spaced
tees. Viessmann strongly recommends
and prefers the use of a low-loss header
over closely spaced tees. When used in
conjunction with the Vitodens 100-W
boiler, the low-loss header acts as
hydraulic break, decoupling boiler and
system circuits from each other (no
sensor required). It is recommended to
use the low-loss header in applications in
which the total system flow rate exceeds
the maximum or falls below the minimum
flow rate of the Vitodens 100-W boiler.
For maximum boiler flow rates, see the table on page 11
in this manual.
Viessmann strongly recommends the use of a low-loss
header in cases where the system head and flow rates
are unknown.
In addition, the low-loss header helps eliminate air and
debris [D] from the heating system. See illustrations for
Low-loss header design and the principle of operation.
Product may not look exactly as illustrated.
Low-loss header design
18
Vitodens 100-W, WB1B Technical Data
V
primary
Prinicpal of operation
The low-loss header is available in the following sizes.
Select the size based on the maximum system flow rate
of your application.
Model No.
Type 80/50
Type 120/80
Legend
AB Air Bleed
BR Boiler Return
BS Boiler Supply
BY Bypass
(with laminar flow)
D Debris and/or air
T1 Boiler supply temp.
T2 Boiler return temp.
V Boiler circuit flow rate
primary
V Heating circuit flow rate
secondary
V
bypass Bypass flow rate
Q
Heat supplied by boiler
primary
Q
Heat consumed by system
secondary
V < V
primary secondary
T1 > T3
T2 = T4
Q = Q
primary secondary
T1 176° F (80° C)
V secondary= V primary+ V bypass
IMPORTANT
When installing a low-loss header, system mixed supply
temperature (T3) must be calculated as follows
Product may not look exactly as illustrated.
V V
bypass secondary
Max. system flow rate
17.6 GPM (4 m3/h)
35.2 GPM (8 m3/h)
DV Drain Valve
SR System Return
SS System Supply
TS Viessmann Temp.
Sensor (not used)
SW Sensor Well
T3 System supply temp.
T4 System return temp.