Camus Hydronics Valiant FT VA0080, Manual

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If the boiler’s supply sensor is below a certain temperature,
the boiler turns on to provide the required heat for the DHW.
This temperature is set by the parameter
DHW_Store_Supply_Extra
which adds on to
DHW_Store_Setpoint parameter to determine the minimum
temperature the boiler’s supply sensor must maintain to
satisfy the required heat demand from the DHW tank.
When the boiler turns on to maintain the supply temperature
above the required DHW_Store_Supply_Extra parameter.
If the supply temperature
T_Supply
is below
DHW_Store_Setpoint
+
DHW_Store_Supply_Extra –
DHW_Supp_Hyst_Down
the burner starts as well.
When the burner is ON the power is PID-modulated so
T_Supply
is regulated towards
DHW_Setpoint
+
DHW_Store_Supply_Extra
.
The burner is stopped when the supply temperature rises
above DHW_Store_Setpoint + DHW_Store_Supply_Extra
+ DHW_Supp_Hyst_Up .
The demand for the tank is ended when the tank-sensor
rises above DHW_Store_Setpoint + DHW_Store_Hyst_Up .
The pump continues DHW_Post_Pump_Period .
DHW Priority
Standard DHW demand has priority over CH demand but
the priority period is limited up to DHW_Max_Priority_Time .
The priority timer starts when both CH and DHW demand
are present. After the
DHW_Max_Priority_Time
is
achieved, the control will switch from DHW to CH operation.
CH has priority now for a maximum period of
DHW_Max_Priority_Time .
Different DHW Priority types can be chosen (Default
DHW_Priority
is set to 2):
DHW Priority Description
0: Time DHW has priority to CH during
DHW_Max_Priority_Time
1: OFF CH always has priority to DHW
2: ON DHW always has priority to CH
Table 20: DHW Priority Settings
Store warm hold function
Because of the presence of the store sensor (
T_Store
) the
control can detect demand for holding the store warm. If
T_Store drops below DHW_Store_Setpoint -
DHW_Store_Hold_Warm the burner starts at minimum
power. The burner stops if
T_Store
is higher than
DHW_Store_Se DHW_Store_Hyst_Up
.
5.5.3 DHW Mode 2: Storage with thermostat
In this mode DHW is prepared by warming up a store. Either
a DHW pump or 3-way valve can be used to switch to DHW
mode. The temperature of the DHW in the store is regulated
by a thermostat (instead of a sensor), which should provide
only an open/closed signal to the control.
When the thermostat closes the control detects a demand
for the tank and starts the DHW pump.
If the supply temperature
T_Supply
drops below
DHW_Store_Setpoint – DHW_Supp_Hyst_Down the
burner starts.
When the burner is ON the power is PID-controlled based
on
T_Supply
toward
DHW_Store_Setpoint
.
The burner is stopped when the supply temperature rises
above
DHW_Store_Se DHW_Supp_Hyst_Up
.
The demand for the store is ended when the store
thermostat opens. The pump continues
DHW_Post_Pump_Period after the DHW demand stopped.
DHW Priority
Standard DHW demand has priority over CH demand but
the priority period is limited up to DHW_Max_Priority_Time .
The priority timer starts when both CH and DHW demand
are present. After the
DHW_Max_Priority_Time
is
achieved, the control will switch from DHW to CH operation.
CH has priority now for a maximum period of
DHW_Max_Priority_Time .
5.5.4 DHW Mode 3: Instantaneous water heating with
plated heat exchanger, flow switch and DHW-out
sensor
In
DHW_Mode
3 the water flow through a plated heat
exchanger is checked with a flow switch. Either a DHW
pump or 3-way valve can used to switch to DHW mode. If
the switch closes, a water flow is detected and the DHW
pump is started. The temperature of the DHW is set with
DHW_Setpoint
.
If the
DHW_Out
sensor drops below
DHW_Setpoint –
DHW_Hyst_Down the burner starts. When the burner is ON
the power is PID-controlled based on
T_DHW_Out
toward
DHW_Setpoint . The burner stops when the T_DHW_Out
temperature rises above
DHW_Se DHW_Hyst_Up
.
When the flow switch opens the demand for the tapping is
ended and the burner stops. The pump continues
DHW_Post_Pump_Period .
5.5.5 DHW Mode 4: Instantaneous water heating with
plated heat exchanger and DHW-out sensor.
In DHW mode 4 the DHW_Out sensor ( T_DHW ) is used for
both detecting DHW tapping and modulating the burner to
the required DHW_Setpoint . Either a DHW pump or 3-way
valve can be used to switch to DHW mode.