Heating circuit control
69
if heating circ. pump =
off
Mixer
Mixer action after shutdown of the pump (unless Enable heating
circuit = Off):
Available for selection: Close, Open, Unchanged, (continue to)
Regulate
if enable mixer = off
Mixer
Mixer action when Enable mixer = Off:
Available for selection: Close, Open, Unchanged
➢ If one of the shutdown conditions is active, the heating circuit pump will be shut down and the
set flow temperature will be set to +5 °C.
➢ If an external set room temperature is specified (input variable), shutdown conditions apply
as follows:
• If the value of the input variable is ≥ the standard temperature parameter T.room standard,
the heating circuit is in standard mode. Therefore the shutdown conditions for standard
mode apply.
• If the value of the input variable is ≥ the setback temperature parameter T.room setback
and < T.room standard, the heating circuit is in setback mode. Therefore the shutdown
conditions for setback mode apply.
➢ None of the parameter values have an adjustable hysteresis. The switching thresholds are
each divided into a start differential and a stop differential.
➢ As the calculation of the set flow temperature incorporates both the outside temperature and
the room temperature (provided a sensor is in use), the shutdown if T.flow Set < min. is the
method used most frequently. This shutdown condition is the controller factory setting.
➢ The mixer action for "if enable mixer = off" is dominant over "if heating circ. pump = off".
Parameters in the Frost protection sub-menu
This function section becomes active in Standby mode in any operating status, even if the heating
circuit is currently partially disabled via the Enable pump input variable or if a shutdown condition
would prevent operation of the heating circuit pump.
If Enable mixer is set to OFF, the pump remains switched on and frost protection mode does not
apply. The mixer acts according to the setting in the shutdown conditions for mixer action when
Enable mixer = OFF.
If the function is blocked by Enable heating circuit, frost protection will not operate!
Frost protection is activated when the outside temperature falls below "T.outside av.c.<", the flow
temperature is below "T.flow<" or, if a room sensor is connected, the room temperature falls below
"T.room frost".
When frost protection is activated, the set flow temperature is set to the flow temperature on the
heat curve that corresponds to the room temperature T.room frost, but must be at least T.flow min.
or T.flow min. standard according to the time condition status (setting in the Heat curve sub-menu).
If there is no outside temperature linked to the function, the value for the average outside
temperature is set to 10.0 °C. In this configuration, the frost protection mode is not activated by the
outside temperature if the frost protection threshold T.outside av.c is below 10.0 °C.
Frost protection mode ends when the temperature that triggered the frost protection function rises
2 K above the applicable frost protection limit (fixed hysteresis).
Start threshold via the outside temperature
• Start threshold via the room temperature
• Set room temperature for frost protection mode
Changeover from standard to setback mode
If frost protection mode is triggered via the outside temperature
threshold when changing from standard to setback mode, it can only
become active after this delay.
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