Siemens RDX42.22U Technical Instructions page 3

RDX42.22U Room Temperature Controller with LCD
Heating Mode
On
Off
Cooling Mode
On
Off
Return air temperature
Siemens Industry, Inc.
The system will switch to Heating mode when the operating mode selector, on the front
of the unit, is set to Heat.
The heating equipment receives the On command via control output terminal 10 when
the following conditions are met:
1. The measured room temperature is half the switching differential below the
setpoint, and
2. The heating output has been off for more than three minutes (adjustable).
The auxiliary heating equipment receives the On command via control output terminal 7
when these conditions exist:
1. Heating output terminal 10 is activated, and
2. The measured room temperature is below the setpoint differential between heating
and auxiliary heating (adjustable with parameter P12).
The heating equipment receives the Off command via control output terminal 10 when
the following conditions are met:
1. The measured room temperature is half the switching differential above the setpoint,
and
2. The heating output has been on for more than one minute (adjustable, see
Parameters).
The auxiliary heating equipment receives the off command via control output terminal 7
when:
1. The measured room temperature is above the setpoint differential between
heating and auxiliary heating (W
2. The auxiliary heating output has been on for more than one minute (adjustable, see
Parameters).
When the operating mode selector is set to Cool, the system will switch to cooling
mode.
The cooling equipment receives the On command via control output terminal 5 when
the following conditions occur:
1. The measured room temperature is half the switching differential above the
setpoint, and
2. The cooling output has been off for more than three minutes (adjustable, see
Parameters.)
The cooling equipment receives the Off command via control output terminal 5 when
these conditions are met:
1. The measured room temperature is half the switching differential below the setpoint,
and
2. The cooling output has been on for more than one minute (adjustable, see
Parameters).
The RDX42.22U provides control based on room temperature or return air temperature.
It detects if a QAH11.1 cable temperature sensor is connected to input terminals 9 and
8, and then operates automatically according to the return air temperature.
) (adjustable with parameters P12), and
D
Technical Instructions
Document Number 155-747
March 13, 2008
Page 3