Siemens RDF870KN Series Manual page 18

PM2.5 & CO2 room unit application (dual duct independent fan control together with a master controller)
Dual duct independent fan fresh air unit or purifier with built-in PM2.5 filter via by-pass
damper
Basic parameter settings: APP = 2, DISP (PM2.5 = 1, CO
FAN1 & FAN2 =1-/3-speed on/off fan
RDF870... unit can be set up as a controller combining PM2.5 and CO
ternal PM2.5 and CO
fresh air unit and purifier (i.e. dual duct independent fan fresh air unit with PM2.5 built-in filter
via by-pass damper). The damper can be disabled (inlet open and by-pass close) or enabled
(by-pass open) via an extra damper input from a master controller.
When the by-pass damper is inactive, the outside air can enter the room via the inlet that is
controlled by a master. The fan speeds are switched as per the actual CO
setpoint.
When the by-pass damper is active via control input from a master controller, the inlet is dis-
abled by the master controller and outside air is blocked. As a result, all the exhaust air (or
partially) will be forced to flow via the by-pass PM2.5 filter and return to the room – air circu-
lates internally. The fan speeds are switched as per the actual PM2.5 level and the PM2.5
setpoint.
If both fans have same fan speed, airflow circulates internally. However, two fans also can
be operated at different speeds to generate different air pressures internally.
18
Siemens
Smart Infrastructure
sensors connected to X1 and X2 respectively to control the fan for a
2
= 1), SEN1 = 3, SEN2 = 4,
2
control with an ex-
2
level and the CO
2
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