Rotex Controller Series, Product Documentation

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EbV Product documentation THETA NORM/UNIT
8-47
Operating mode 6 – Discharge control to heat generator
System hydraulics:
This hydraulic layout is used when an alternative-energy buffer tank is added to an
existing system. In such systems there are often existing unit boilers with integrated
DHW tank and DHW loading.
All heat requests are sent to the heat generator.
When the buffer tank can cover the energy demand, the heat generator nominal
temperature is maintained by the buffer, via BULP (PLP), instead of the burner.
In this way the heat generator always operates at its nominal temperature and can
not be exposed to excessive buffer temperatures.
See the table below for detailed correlations.
Buffer operating mode
1 2 3 4 5 6
Buffer request from HC/DHW HC HC/DHW HC HC ---
H-GEN request from BUFFER BUFFER/
DHW
BUFFER BUFFER/
DHW
BUFFER/
DHW
HC/DHW
Buffer control type Charge Charge Discharge 1 Discharge 1 Charge Discharge 2
Buffer start-up protection acts on HC/DHW HC HC/DHW HC HC ---
Buffer discharge protection X X --- --- X ---
Buffer frost protection monitoring X X --- --- X ---
Buffer minimum temperature
monitoring
X X --- --- X ---
Buffer maximum temperature
monitoring X X X X X X
Buffer forced dissipation into HC/DHW HC HC/DHW HC HC HC/DHW
Buffer skimming function X X* --- --- X* ---
Loading temperature control from HC/DHW HC --- --- HC ---
H-GEN start-up protection on
BULP X X --- --- X ---
Function BULP without request OFF OFF OFF OFF OFF OFF
Function BULP for manual
operation ON ON OFF OFF ON OFF
Function BULP for sensor defect ON ON OFF OFF ON OFF
Function BULP for heat
generator disabled --- --- ON ON --- ---
Function BULP if H-GEN not
available and buffer start-up
protection is active** --- --- OFF OFF --- ---
Function BULP if H-GEN
available and buffer start-up
protection is not active** --- --- ON ON --- ---
Effect of H-GEN start-up
protection on BULP DHW/BULP HC/DHW HC/DHW BULP HC/DHW
Tank discharge protection / H-
GEN in system BULP H-GEN H-GEN H-GEN H-GEN H-GEN
Tank discharge protection / no H-
GEN in system BULP H-GEN BULP H-GEN H-GEN H-GEN
OS
BU
BULP
BS
HC-P
VF1
VF2
MC1
MC2
SOL-P
DHWS
BU
Buffer
Heat
generator
Domestic hot
water
tank