Function Description Control Unit; Heating Mode; Heating The Loading Cylinder; Operating The Fuel Cell Module - Viessmann Vitovalor PT2 E11T Installation And Service Instructions Manual

Function description
Control unit

Heating mode

The control unit determines a set flow temperature for
the heat generator, subject to the outside temperature
or the room temperature and the slope/level of the
heating curve.
The determined set flow temperature is transferred to
the burner control unit. The burner control unit calcu-
lates the modulation level from the set and actual
boiler water temperatures and regulates the burner
accordingly.

Heating the loading cylinder

The circulation pump of the gas condensing module or
the fuel cell module is switched on and the corre-
sponding 3-way diverter valve is changed over if the
cylinder temperature sensor detects a temperature
lower than the predefined set value.
■ The cylinder loading pump is switched on when the
heat generator flow temperature is
temperature.
■ The burner is switched on when the heat generator
flow temperature is the set cylinder temperature,
≤
and the cylinder loading pump is switched on when
the required flow temperature is reached.

Operating the fuel cell module

The fuel cell module is switched on to generate power
according to the heat-up condition of the integral DHW
cylinder and the energy manager defaults. Heating
energy generated during operation is directed to the
DHW cylinder or the heating circuits.
If the energy manager is enabled, the fuel cell module
starts to best meet the power demand. Start times will
depend, among other things, on the consumption pat-
tern in the household mains.

Connection, heating circuit pump for heating circuit without mixer

Only for systems with several heating circuits
186
The electronic temperature limiter inside the burner
control unit limits the flow temperature.
The loading cylinder is heated up to the set cylinder
temperature. Heating stops when the specified temper-
ature has been reached at the cylinder temperature
sensor.
After loading has stopped, the cylinder loading pump
and the 3-way diverter valve remain on for 30 s more.
the set cylinder
≥
If the energy manager is disabled, the fuel cell module
starts solely on the basis of heat demand.
After operation, the regeneration phase of the fuel cell
module starts.
The fuel cell module process allows an operating
period of 45.5 h per start.
If the maximum return temperature on the fuel cell
module has been reached, the module shuts down.
If a heating circuit without mixer is connected down-
stream of the low loss header, the circulation pump
can be connected to output P1 (see page 34). The
function of output P1 is set in the commissioning assis-
tant.