Siemens RVL481 - Collector Temperature to Protect against Overheating; Storage Tank Recooling

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Siemens Heating and D.h.w. Controller RVL481 CE1P2541en
Building Technologies 26 Function block "D.h.w. solar charging" 20.05.2008
26.2.5 Collector temperature to protect against overheating
Operating line 204 allows for setting the temperature protecting the collector against
overheating.
If there is a risk of overheating at the collector, storage tank charging is continued past
the charging temperature maximum limitation (set on operating line 206) to the storage
tank temperature maximum (set on operating line 207) to reduce the amount of surplus
heat.
Collector overheating protection is no longer possible and the collector pump is
switched off after the storage tank temperature maximum limitation is reached.
T
ON
OFF
t
TSp
2541D15
1 °C
1 °C
TSpMax
TSpSi
TKol
TKolUe
TSpSi Storage tank temperature maximum limitation
TSp Storage tank temperature
TKolUe Collector overheating protection temperature
TSpMax Charging temperature maximum limitation
TKol Collector temperature
ON/OFF Collector pump
T Temperature
t Time
• The collector pump is switched on if the collector temperature exceeds the collector
temperature overheating protection temperature and if the storage tank temperature
maximum limitation is not yet reached: TKol > TKolUe and TSp < TSpSi.
The collector pump is switched off if the collector temperature drops by 5 K below the
overheating protection temperature: TKol < TKolUe – 5 K
• The collector pump is switched off if the current storage tank temperature reaches the
maximum limitation:
TSp > TSpSi
The collector pump is again switched on if the storage tank temperature drops by 1 K
below the d.h.w. storage tank temperature maximum limitation:
TSp < TSpSi – 1 K
In the case of two storage tank sensors, the hotter of the two is the decisive sensor.
Setting --- switches off collector overheating protection.
26.2.6 Storage tank recooling
Function "Storage tank recooling" cools down d.h.w. storage tank – after collector over-
heating protection – to a lower temperature level.
Storage tank recooling is carried out via collector surface. In this case, the energy of
the d.h.w. storage tank is emitted in the environment via the collector surface by switch-
ing on the collector pump.
The recooling setpoint (TRk) is set to a fixed 80 °C.
The switching differential for recooling (SDON) corresponds to the value of the switch-
on differential (operating line 201) of charge control, but is limited to min. 3 K for recool-
ing.