Function Description Of Solar Dhw Heating; Suppression Of Dhw Cylinder Reheating By The Boiler - Viessmann EM-S1 Installation And Service Instructions For Contractors

Function description of solar DHW heating

Note
Set or alter the functions described below in the
parameters in the "Solar" group.
Parameter
Number Designation
The solar circuit pump is switched on according to the following criteria, resulting in the DHW being
heated:
1126.0 "Collector minimum tempera-
ture"
1492.0 "Start temperature differen-
tial, solar circuit pump"
The solar circuit pump is switched off if one of the following criteria is met:
1125.0 "Maximum cylinder tempera-
ture for solar DHW heating"
1126.1 "Maximum collector tempera-
ture"
1492.1 "Stop temperature differen-
tial, solar circuit pump"
— —
Further parameters:
1118.0 "Minimum speed of the solar
circuit pump"
1118.1 "Maximum speed of the solar
circuit pump"

Suppression of DHW cylinder reheating by the boiler

Reheating of the DHW cylinder by the boiler is sup-
pressed when the set DHW temperature for reheating
is reduced by the boiler.
During reheating suppression, the DHW cylinder is
only heated by the boiler if the cylinder temperature
falls below the set DHW temperature for reheating.
Start of reheating Duration of reheating suppression
suppression
Stage 1
Solar circuit pump on Solar circuit pump runtime x 6
Example:
Solar circuit pump runtime: 0.5 h
0.5 h x 6 = 3 h reheating suppression
Pump runtimes that occur during the run-
time of reheating suppression are calcula-
ted according to the formula and the result
is added to the remaining runtime of the
previous reheating suppression.
Description
The solar circuit pump is started when the minimum collector
temperature set in parameter 1126.0 is exceeded.
The temperature differential between the cylinder tempera-
ture and the collector temperature is greater than the start
temperature differential set in parameter 1492.0.
The maximum cylinder temperature (set DHW temperature)
set in parameter 1125.0 is exceeded.
If the maximum collector temperature set in parameter
1126.1 is exceeded, the solar circuit pump is switched off to
protect the system components (emergency collector shut-
down).
The solar circuit pump will restart when the collector temper-
ature falls to 20 K below the set value.
The temperature differential between the cylinder tempera-
ture and the collector temperature is smaller than the stop
temperature differential set in parameter 1492.1.
The temperature set at the temperature limiter (if installed) is
exceeded.
Minimum speed of the solar circuit pump adjustable in %.
Delivered condition: 23 %
Maximum speed of the solar circuit pump adjustable in %.
Delivered condition: 84 %
The duration of reheating suppression is based on the
runtime of the solar circuit pump and takes place in 2
stages.
Set DHW temperature for reheating by
the boiler
Average of the set DHW temperature and
the value set in parameter 1394.0
Example:
Set DHW temperature: 50 °C
Value set in parameter 1394.0: 40 °C
Calculated set DHW temperature for reheat-
ing by the boiler: 45 °C
Function description
17