Viessmann Vitodens 200 WB2 Series Technical Data Manual page 42

Installation Examples
System Layout 5
Vitodens 200 (up to model WB2 8-32) with...
– direct-connected heating circuit
– one heating circuit with system separation
AV
PRV
TPV
Y
Important:
Installation of different heating circuits...
Please note location of expansion tank
H radiator heating circuit (high temperature
circuit)
H underfloor heating circuit with 3-way
mixing valve (low temperature circuit)
H DHW production
...with the following flow conditions
1. The flow rate (output) of the radiator
heating circuit is at least 30% greater than
that of the underfloor heating circuit.
2. The total flow rate of the two heating
circuits is less than the maximum possible
water flow rate of the Vitodens 200 boiler
(see following table).
Model No. Max. flow rate
(GPM/ltr/h)
Vitodens 200,
WB2 6-24C 6.2/1400
WB2 6-24 6.2/1400
WB2 8-32 7.0/1600
The use of a low-loss header is strongly
recommended if the maximum water flow
rate in the application concerned exceeds
the values shown in the preceding table, or
if the system flow rates are unknown.
The low-loss header is available as an
accessory part.
42
I
M
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See preceding pages for installation
examples with a low-loss header.
See page 34 in this manual for details on
the low-loss header.
The 3-way mixing valve, built-in to achieve
the low temperature level of the underfloor
heating circuit, is controlled by an accessory
kit for a heating circuit with mixing valve.
The circulation pump built into the Vitodens
200 boiler supplies the radiator heating
circuit and the plate heat exchanger for
system separation. The underfloor heating
circuit is supplied by a circulation pump
installed on site which is controlled by the
accessory kit.
Upon a call for DHW, the built-in diverting
solenoid valve is energized. The boiler hot
water is diverted to the DHW loop at
maximum pump rotational speed (no
variable speed pump operation during DHW
production). Once the DHW tank is
satisfied, the built-in diverting solenoid valve
is de-energized and heating operation
resumes.
AV Air vent
PRV Pressure relief valve
TPV Temperature and pressure relief
valve
Vitodens 200 gas-fired condensing
boiler with programming unit for
weather-responsive operation
Outdoor temperature sensor
Remote control for programming unit
Underfloor heating circuit
Radiator heating circuit
Plate heat exchanger for system
separation
Heating circuit pump (field supplied)
Mixing valve temperature sensor
I
Accessory kit for heating circuit with
mixing valve
DHW storage tank
DHW tank temperature sensor
Expansion tank
Optional purge tee (field supplied) for
easier removal of air
DHW supply and return piping
IMPORTANT
The pressure drop (secondary circuit) of the
plate heat exchanger must be less
than/equal to (≦) the pressure drop of the
3-way mixing valve.
This must be taken into account when
sizing the plate heat exchanger.
IMPORTANT
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 the residual
head of the built-in pump 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 residual 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.