With Dpc1 Thermostat; With External Control; Switching Of The Main Components; Indoor Fan - Johnson Controls York YKN2Open board Technical Information

4 Operation
4.3

Switching of the main components

• The electric resistors have less priority than the compressors (to generate heat) and they are arranged
in order of operating hours. Those that have not activated the thermal switch protection activate to
generate heat.
• The gas stages are not arranged in order. Stage 1 will always have the highest priority. In heat pump
units, they have less priority than the compressors in accordance with the outside temperature.

4.2.1 With DPC1 thermostat

With thermostat operating by communication, if there is demand (Y1) and a stage in operation, the stage
is activated and management of the other two stages is begun (be it cool or heat).
While there is demand (Y1), the error between the setpoint and the room temperature is calculated each
minute.
• If the error is equal to or more than (unfavourable tendency) the previous minute, the number on a
counter is increased.
• If the counter reaches 10 another stage is activated (as long as it is present and available) and the
counter resets to 0, in order to calculate another demand.
When the thermostat demand disappears (Y1), all the stages that the demand control unit has activated
are stopped.

4.2.2 With external control

A different thermostat to the DPC-1 can be used as long as it is 24 V
contacts for the standard signals G, Y1, Y2 and O/B.
If an external control is used with an ambient temperature probe and non-live contacts, the following
sequences must be generated in order to generate the different operation modes:
• R-G Indoor fan.
• R-G-Y1 Cool mode 1 stage.
• R-G-Y1–Y2 Cool mode 2 stages.
• R-G-O/B-Y1 Heat mode 1 stage.
• R-G-O/B-Y1-Y2 Heat mode 2 stages.
If more than 2 stages are available, the demand control unit activates stages every 10 minutes.
When the demand disappears (Y2), all the stages that the demand control unit has activated are stopped.
In order for correct operation in cool or heat mode, the position of microswitches SW5, SW6 and SW7
must be taken into account.
4.3 Switching of the main components

4.3.1 Indoor fan

N O T E
[See the operating parameters in the section Rooms, see on page 25].
The operation can be continuous or automatic.
• Automatic operation only activates when there is demand for cold or heat.
• Continuous operation can be selected on the thermostat.
Its status is determined by the G signal on the thermostat, except if there is a fault in the thermal switch,
which stops the fan.
In automatic fan mode:
• The indoor fan is in operation whenever any stage is in operation (heat, cool or auxiliary heat).
10
and has outputs with non-live
AC