Suppression Of Dhw Cylinder Reheating By The Heat Generator; Suppression Of Reheating By The Boiler In Relation To Central Heating Backup (Not In Conjunction With Heat Pumps); Maximum Collector Temperature; Minimum Collector Temperature Limit - Viessmann SDIO/SM1A Installation And Service Instructions Manual

Version with SM1 and KM-BUS

Suppression of DHW cylinder reheating by the heat generator

In systems with boilers
Reheating is suppressed in 2 stages:
■ Reheating of the DHW cylinder by the boiler is sup-
pressed as soon as the solar circuit pump starts up.
For this, half the suppression becomes effective in
stage 1 (example: Set DHW temperature of 50 °C
and set DHW temperature for solar reheating sup-
pression of 40 °C results in a reduced enabled set
value of 45 °C). If the DHW temperature falls below
the reduced enabled set value, the boiler carries out
reheating. After the solar circuit pump has been
switched off, suppression remains active for a certain
time.
In the case of uninterrupted heating by the collectors
■
( 2 h), full suppression is activated. The reduced set
>
DHW temperature now applies. If the DHW tempera-
ture falls below the reduced enabled set value, the
boiler carries out reheating. Reheating suppression
ends as soon as the solar circuit pump is switched
off.
The reduced set DHW temperature is specified in
coding address "67" or parameter "0C" in the "DHW"
group. This value must be below the first set DHW
temperature.
Suppression of reheating by the boiler in relation to central heating backup (not in conjunction
with heat pumps)
Reheating by the boiler is suppressed if a sufficiently
high temperature for heating the heating circuits is
available in the multi mode heating water buffer cylin-
der. The temperature is dependent on the required
flow temperature of the heating circuits.

Maximum collector temperature

If the maximum collector temperature set in coding
address "09" is exceeded, the solar circuit pump is
switched off to protect the system components (emer-
gency collector shutdown).

Minimum collector temperature limit

The solar circuit pump is started when the minimum
collector temperature set in coding address "12" is
exceeded.
(cont.)
In systems with heat pumps
During solar DHW heating, the "Set DHW tempera-
ture" is reduced by 5 K.
If the collector temperature falls 20 K below the set
value the solar circuit pump starts again.
Function description
23