Regio Midi manual
Chapter 12
Special functions
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Chapter 12 Special functions
Change-over function
Change-over is a function for installations with 2-pipe systems. It makes it possible to use the
same pipe for both heating and cooling, depending on requirements during for example the
summer (cooling output) and the winter (heating output).
Control modes
To activate the change-over function, control modes "Heating or Cooling via change-over" or
"Heating/Heating or Cooling via change over" needs to be configured.
All controllers in the Regio series have an input for change-over. To be able to configure the
control mode "Heating/Heating or Cooling via change-over", it is necessary to have a Regio
Midi controller with fan function. The input can be either of the type analogue PT1000-sensor
or a closing contact connected to a digital input (FS=PT1000-input).
Change-over digital
When using a digital signal input (potential-free contact), closing the contact will activate the
change-over function and set the heating output, UO1 alt. DO2/DO3 (-T-models), to cooling.
On open contact, the change-over function will set the heating output to heating.
Change-over analogue
There are two different analogue change-over modes, simple and advanced. In both cases, a
temperature sensor must be connected to an analogue input to measure the media temperature.
Change-over simple
In simple mode, the change-over state is set to cooling when the change-over temperature goes
below the low limit. It is set to heating when the change-over temperature exceeds the high
limit.
Change-over advanced
In advanced mode, the change-over function will measure the difference between the room
and media temperature. As long as the heat valve is more than 20 % open, or every time a
valve exercise is performed, the difference between the media and room temperature will be
calculated. If the temperature difference is greater than the configured value (differs for
Heating and Cooling mode), the control mode will change. The factory settings for the
difference between Heating and Cooling change-over are:
•
Change from Heating to Cooling = 4K
•
Change from Cooling to Heating = 3K
This setting may be changed using parameters number 9 and 10.
Forced ventilation
All Regio midi controllers have functionality for forced ventilation. All controllers except RC-
C3DFOC have a digital output for controlling a forcing damper to increase the airflow to the
room. This output is always activated in operating mode Bypass.
When control mode “Heating/Cooling with VAV-control and forced supply air function” is
active, the cooling output is used to control the forcing damper. When forced ventilation is
active, the cooling output is set to full cooling, regardless of what the controller output signal
is.
Models RC-C3/RC-C3H/RC-C3O/RC-C3DOC/RCC-C3DOCS can select whether the forced
ventilation output should be a 0…10 V analogue output or a 24 V digital output (parameter
22).
