Viessmann EM-S1, Installation And Service Instructions For Contractors

18

Start of reheating
suppression

Duration of reheating suppression

Set DHW temperature for reheating by
the boiler

Stage 2

Solar circuit pump on
> 120 min

Runtime of the solar circuit pump + 24 h

■

Solar circuit pump running:
Value set in parameter 1394.0

■

Solar circuit pump off:
As for stage 1

Reduction of stagnation time

If there is an excess of solar energy, the speed of the
solar circuit pump is reduced before the maximum cyl-
inder temperature is reached (parameter 1125.0). This
causes an increase in the differential between collector
temperature and cylinder temperature. The heat trans-
fer to the DHW cylinder is reduced, which delays stag-
nation.

The temperature differential for reducing the stagna-
tion time can be adjusted in parameter 1505.
This function can only be implemented in systems with
a variable speed solar circuit pump.

Collector frost protection

Viessmann collectors are filled with Viessmann heat
transfer medium. Consequently, this function does not
need to be enabled.
Only enable it if water is used as the heat transfer
medium.

To prevent damage to the collectors, the solar circuit
pump is switched on if the collector temperature falls
below +5 °C. The pump is switched off when +7 °C is
reached.
Note parameter 1127.0.

Interval function solar circuit pump

Set parameter 1719.0.
Activate the interval function in systems where the col-
lector temperature sensor is not in an ideal location, to
prevent a time delay in capturing the collector temper-
ature.

For correct capture of the collector temperature, the
interval function cyclically switches on the solar circuit
pump for brief periods.

Relay kick

To prevent the pumps and valves from seizing up, they
are started for about 10 s every 24 h.

Function description

Function description of solar DHW heating

 (cont.)

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Appendix