Siemens RDG20 KN Series Basic Documentation page 74

Functions
4
Additional functions
Frost protection (P109)
CO control versus
2
temperature control
CO sensor calibration
2
Installation and
commissioning
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Notes:
•
When On/Off damper is selected, the fan speed depends on the higher fan
request between temperature demand and IAQ demand.
•
For energizing the damper during IAQ demand, select "IAQ damper"
P453 = 3 (normally close). This logic can be inverted by selecting P453 = 2
(normally open).
When fresh air from outside is provided to the equipment, IAQ frost protection
should be enabled to protect the coils (set P109 frost setpoint).
If the outside temperature value from bus (sent to RDG via e.g. LTE-mode, zone
31) is below the setpoint, the frost protection function closes the damper. When
outside temperature increases 2K (hysteresis) above the setpoint, the damper is
opened again.
When fan is disabled (P350 = 0) or setting the application as 4-pipe with 6-port
valve (H/C no fan), the frost protection is not supported.
The CO control has higher priority than the temperature control.
2
Depending on the dimension of HVAC system, room temperature setpoint may not
be kept when CO control is active.
2
If such problem occurs, the dimension and balancing of HVAC system should be
checked. As an alternative, the CO
RDG2..4KN uses a maintenance free CO
The ASC (automatic self-calibration) algorithm maintains an accurate CO
over time when the thermostat is regularly exposed to the fresh air (400 ppm). As it
is the case in well ventilated buildings over night without human presence or when
windows are opened. In addition, the thermostat always needs to be powered.
Powering off and on the device can cause wrong CO
and delay the ASC procedure.
The DC damper is connected on multifunction output U1. For those applications,
U1 as multifunctional input (P155) is not available.
The CO sensor is very sensitive to all mechanical strengths. Avoid as much as
2
possible mechanical shocks, drops or vibrations during transport or installation,
which could cause a sensible CO
case, it is recommended to wait up to 2 or 3 weeks before retesting the CO
measurement.
setpoint (and P-Band) can be increased.
2
sensor.
2
indications for several days
2
deviation after installation. If this would be the
2
reading
2
2
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