Boiler Connections
30
Installation Examples
(continued)
System Layout 3
Vitodens 100-W, WB1A 8-24, 8-30 with...
– DHW storage tank
– one heating circuit
Primary pump
must pump into
the boiler (as illustrated).
AV Air vent
PRVPressure relief valve
TPVTemperature and pressure relief
valve
Vitodens 100-W gas-fired
condensing boiler
External boiler/DHW controller
(field supplied)
Heating circuit
Heating circuit pump
(field supplied)
DHW storage tank
DHW tank temperature aquastat or
sensor
DHW circulating pump
(field supplied)
Closely spaced tees, 4xpipe Ø
or 12” /305mm
*
Expansion tank
Primary pump (boiler circuit, field
supplied)
*
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.
Please see page 36 for details.
Please note!
The use of a low-loss header is
recommended if the water flow rate is
less
than 1.7 GPM / 400 ltr/h or
more
than 6.2 GPM / 1400 ltr/h.
The low-loss header is available as
accessory part.
See page 36 in this manual for details
on the low-loss header.
Model No.
Vitodens 100-W,
Max. flow rate
(GPM/ltr/h)
WB1A 8-24
6.2/1400
WB1A 8-30
6.2/1400
DHW supply and return piping between boiler DHW connections and the Viessmann DHW tank connections, shall be a
minimum of 1” nominal pipe diameter (irrespective of the ¾” DHW connection outlet sizes provided on the boiler and the
DHW tank). This will ensure pump head is fully utilized to overcome the resistance of the DHW heat exchanger coil and to
provide sufficient water flow to the boiler heat exchanger.
In non-Viessmann DHW tank applications, perform, in addition to the above, accurate calculations for DHW tank coil
pressure drop versus boiler pump head to ensure sufficient water flow to the boiler heat exchanger. Failure to heed the
above instructions may cause boiler short-cycling and inadequate DHW supply.
5
5
8
1
7
7
5
1
.3
AV
PRV
TPV
Y
Y
4xpipe Ø
or 12” /305mm
IMPORTANT
IMPORTANT
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