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Document
Preliminary 003
Access V4.X Configuration manual
13 (33)
2019-05-13
The heater return water temperature is measured using the an
alogue input (”Frost protection sensor”).
Low temperatures will generate an internal, proportional signal that is used to force the heating valve
open thereby preventing freeze-up of the heater.
The internal signal will begin to rise as the frost protectio
n temperature falls below “Alarm limitation
running mode” + “P
-
band running mode” in order to reach 100 % output when the signal has fallen to
“Alarm limitation running mode”.
Frost guard
When ”Internal signal” reaches 100 % or the digital input (”Defrost switch”) is activated, the unit is shut
down, the heating output is set to completely open mode and an alarm is activated. The unit is restarted
when the alarm has been acknowledged and the temperature for the frost protection sensor has risen
above “Alarm
limit frost” + “P
-
Band”.
The frost protection alarm limits is set in the:
Settings:
Data & settings > Temperature control > Heating and/or Heating 2.
Standby mode
If frost protection is activated, the controller will go into ”Standby mode” when the runni
ng mode
switches to ”Off”. The “Standby mode” will control the heating output to maintain a constant settable
temperature at the frost protection sensor “Setpoint Standby mode”.
Electric heating
Control
The heating is controlled using the analogue output and/or signal for start heating or step controller to
control 1..4 digital output steps.
Overheat protection
On Activate of the digital input “Overheated electric heater” the unit will be shut down, either according
to the stop sequence described in section Start/stop of unit or as an emergency shutdown. The unit will
restart after the alarm has been acknowledged and “Electric heating is overheated” has reset.
Flow switch
Note that activation of the input signal “Flow switch” will also stop the unit. Note: I
t is important that
the high temperature thermostat is hardwired to disconnect the power to the heater. That is to ensure
that the heating is shut down when the thermostat is activated even if the Access controller should be
faulty.
Fast stop on overheating
If the function "Fast stop on overheating" is active, the fans will be immediately stopped when there is
an overheating alarm, regardless of the set cool-down time.
Step controller heating
Activation:
By configuring the electrical heater the step switch will be activated in the menu.