User Manual

Functions
Control sequences
4
62 | 146 A6V11545892_en--_a
4.7.6 2-pipe/2-stage heating or cooling
On 2-stage applications, the thermostat controls 2 valves or 2-stage compressors
in heating or cooling mode or changeover (automatically or manually).
"Cooling only" is factory-set (P001 = 1).
In heating mode, the 1
st
stage is activated if the acquired temperature is below the
setpoint.
The 2
nd
stage is activated if the acquired room temperature drops below "setpoint"
minus "setpoint differential".
In cooling mode, the 1
st
stage is activated if the acquired temperature is above the
setpoint.
The 2
nd
stage is activated if the acquired room temperature rises above "setpoint"
plus "setpoint differential".
With the swap function enabled, the 1
st
stage in heating (YHC1) switches to the 2
nd
stage in cooling. This function optimizes the use of heating/cooling energy in
systems with different equipment. For example, fan coil units combined with radiant
heating/cooling panels or floor heating/cooling. See Additional functions [➙ 41] to
enable the function via P254.
Depending on the equipment, fan control needs to be started in the 2
nd
stage (in
the 1
st
stage the fan remains OFF), either in the heating or cooling sequence. To
cover the requested application, the fan can be enabled and disabled in different
sequences. For further details, see Fan control [➙ 84].
In the 2-pipe/2-stage application, with parameter P200 “number of heating/cooling
sequences”, it is possible to limit the number of outputs to one cooling sequence
(P200 = 2) or to one heating sequence (P200 = 3).
P200 = 1 2 sequence heating, 2 sequence cooling
P200 = 2 2 sequence heating, 1 sequence cooling
P200 = 3 1 sequence heating, 2 sequence cooling
The diagrams below show the control sequence for On/Off control.
Heating mode (P001 = 0) Cooling mode (P001 = 1)
Changeover (P001 = 2 or P001 = 3,
P254 = 0)
Changeover (P001 = 2 or P001 = 3,
P254 = 1) (swap function)
Changeover
cooling
Changeover
cooling
(YHC2: 1
st
sequence)
Changeover
heating
Changeover
heating
Limit number of
heating/cooling sequence
2-stage heating or cooling
Heating mode
Cooling mode
Swap function
On/Off output
Fan in the 2
nd
stage