Table of Contents
Advertisement
Siemens Building Technologies
HVAC Products
An error message will be generated only when there is no actual room temperature
value available. This is the case when no room unit is used or when the room tempera-
ture measuring circuit is faulty.
The error message means:
• The controller's LCD displays Er
• When querying the outside temperature on the QAW70 room unit (if present), its
display shows --- if there is a short-circuit or open-circuit
4.4
Room temperature (A6)
4.4.1
Types of sensors
The room temperature is acquired via PPS (point-to-point interface); only a unit with an
appropriate output signal can be connected to it. The following types of units can be
used:
• Room unit QAW50...
• Room unit QAW70
• Room temperature sensor QAA10
Its sensing range is 0...32 °C
If a room unit or room sensor is used in both heating circuits, one of the 2 devices must
be addressable. This means:
• The first room unit can be a QAA10, QAW50, QAW50.03 or QAW70
• The second room unit must then be a QAW50.03 or QAW70, addressed with 2
4.4.2
Handling faults
A short-circuit in the measuring circuit leads to an error message.
An open-circuit in the measuring circuit does not lead to an error message since it is
not possible to have a room unit connected.
If the room unit detects a fault in the room temperature measurement (short-circuit or
open-circuit), an appropriate signal will be passed to the RVD240.
4.4.3
Room model
The RVD240 uses a room model for each heating circuit that is ready integrated in the
controller. It simulates the room temperature based on the progression of the outside
temperature and the type of building construction, using a defined attenuation. In plants
with no room temperature measurement, the room model ensures optimum start con-
trol.
4.5
D.h.w. temperature (B3)
4.5.1
Measured variable
With all types of d.h.w. plants, the temperature of the d.h.w. flow is acquired at input
B3.
4.5.2
Types of sensors
The following types of sensors can be used:
• All types of sensors from HVAC Products with a sensing element LG-Ni 1000. Suited
for d.h.w. applications is the immersion temperature sensor QAE2... . Its range of
use is 0...130 °C
Basic documentation RVD240
4 Acquisition of measured values
25/126
CE1P2384en
27.05.2004
Advertisement
Table of Contents
