4.6.3 Output functions
The changeover sensor ensures changeover between heating and cooling mode
based on the acquired water temperature. We recommend activating the Purge
function (P251) with 2-port valves. This function ensures correct acquisition of the
medium temperature even if the 2-port valve is closed for an extended period of
time. The valve is opened for 1 to 5 minutes (adjustable) at 2-hour intervals during
off hours.
The function is valid for outputs PWM, On/Off, On/Off 3-wire, DC, 3-position and all
2-pipe applications.
Limit the On/Off switching cycle to protect HVAC equipment, e.g., compressor and
reduce wear and tear. The minimum output on-time and off-time for the On/Off
control output can be adjusted from 1 to 20 minutes via P212 and P213. The
factory setting is 1 minute.
Readjusting the setpoint or heating/cooling mode changeover immediately results
in calculation of the output state; the outputs may not hold the minimum 1-minute
On/Off time.
If P212 or P213 is set to greater than 1 minute, the minimum On/Off time for the
control output is maintained as set, even if the setpoint or changeover mode is
readjusted.
For 2-pipe and 2-stage applications with different equipment, e.g., fan coil units
and radiant heating/cooling panels, it is possible to invert the sequence of the
equipment to optimize energy use, when the thermostat changes the sequence
from heating to cooling (P001 = 2 or 3).
Under factory settings, the 1
st
stage in heating (YHC1) is also the 1
st
stage in
cooling.
The swap function optimizes use of heating/cooling energy in mixed systems. E.g.,
when the fan coil units are combined with radiant heating/cooling panels, it is better
to start heating using the panels (1
st
stage heating, YHC1) and start cooling using
the fan coil unit (1
st
stage cooling, YHC2).
Enable the swap function by setting P254 (YHC2 output signal, 1
st
stage in cooling)
to ON, depending on the requested control signal.
● For 2-pipe/2-stage applications, see 2-stage on 2-pipe/4-pipe heating and
cooling [➙ 85].
● If the equipment requests fan operation only in the 2
nd
stage (heating and/or
cooling), see Fan control [➙ 108] to set up the fan function (fan in the 2
nd
stage).
● For application examples, see Swap function and/or fan in the 2nd stage
[➙ 172].
All heating sequences can also be used for floor heating.
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