Room Temperature (A6); Types Of Sensors; Handling Faults; Room Model - Siemens RVD230 Basic Documentation

Siemens Building Technologies
HVAC Products
• Plants with a room temperature sensor:
The controller switches over to room-compensated control
• Plants without a room temperature sensor:
The controller operates with a fixed outside temperature of 0 °C
An error message will only be generated 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 dis-
play 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
The sensing range is 0...32 °C
4.4.2

Handling faults

A short-circuit in the measuring circuit leads to an error message.
An open-circuit in the measuring circuit will 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 acquisition (short-circuit or
open-circuit), an appropriate signal is passed to the RVD230.
4.4.3

Room model

The RVD230 uses a room model 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 tem-
perature acquisition, the room model ensures optimum start control.
4.5 D.h.w. flow temperature (B3 and B12)
4.5.1

Measuring variable

With most types of d.h.w. plants, the temperature of the d.h.w. flow is acquired at input
B3. As an option, with plant types 0–10, 1–10, 2–7, 5–10 and 6–7, input B12 is also
used for the d.h.w. flow temperature. With these types of d.h.w. plants, this temperature
can be acquired at 2 locations (e.g. before and after the d.h.w. heat exchanger).
4.5.2

Types of sensors

The following types of sensors can be used:
• Sensor input B3:
Basic Documentation RVD230
4 Acquisition of measured values
25/130
CE1P2383en
27.05.2004