CM2N3204E / 05.2001
Siemens Building Technologies
6/20
Landis & Staefa Division
Integral limit controller for HR equipment such as thermal wheel type heat exchangers,
plate heat exchangers, and glycol circuits: Setpoint, P-band and integral action time are
adjustable. The limit controller is active only when the plant is in operation (fan speed I
or II).
Using the sensors connected to signal inputs Z, B1 and B2, the controller acquires the
actual temperatures. The manipulated variables delivered by the integral limit and
temperature controllers are compared with one another with the help of a priority
selector which selects the manipulated variable with the smallest value (minimum
selection). This manipulated variable reduces the output of the HR equipment. Since a
certain amount of heat is not now available from the HR equipment, the balance is
delivered by a downstream air heater battery (terminal Y10).
An additional sensor must be installed if this function is used. Three temperature values
(temperature behind the heat recovery equipment, outdoor air and extract air tempera-
tures) are required to calculate efficiency. The calculated value is shown on the control-
ler and it generates an alarm if it falls below an adjustable threshold value.
To display data points 103 to 111, set DIL switch No. 2 to the left (ON).
The efficiency calculation acts as a fault indicator, for example, for defective, polluted or
incorrectly connected heat recovery equipment.
This function (display / alarming) is supported by the integration solutions FLN (
AZI65.1
/
UNIGYR, VISIONIK) and LON / BACnet (
AZI65.2
/ DESIGO 30).
When this function is used, the Z-input is not available for other functions.
The start-up mode is only used with the heating sequence Y30 with operating action "/"
(plants using recirculated air dampers). On plant start-up, either supply air temperature
control or one of the two cascade control modes is activated.
The period of time for start-up mode can be set from 0 s to 60 min. During this time, the
cooling sequence (Y20) is disabled and the hot water circulator (Y10) is activated. The
plant operates with 100 % recirculated air (pre-purging).
In the case of plants that use outside sensors, this function becomes active only at
outside temperatures below 15 °C.
In the case of plant start-ups initiated by "Unoccupied heating mode", "Unoccupied
cooling mode" or "Night purging", this function remains inactive.
Plant operation can be controlled from the following locations:
Manual switch (operating level 1: buttons 1 to 4), communication (FLN bus), "External
switch" (E7, E8), "Extended operation" (E7, E8), scheduler program, "Demand con-
trolled ventilation", "Unoccupied heating mode", "Unoccupied cooling mode", night
purging, fault, commissioning.
•
From an external switch:
The functions of the manual switch on the RWI65.02 (operating level 1, buttons 1
to 4) can be provided by a 4-step rotary switch with two levels.
•
By the function "Extended operation":
When a pulse (of at least 3 s) is fed to E7, the plant is operated at fan speed I;
When a pulse (of at least 3 s) is fed to E8, the plant is operated at fan speed II.
•
Scheduler program:
The scheduler integrated in the RWI65.02 facilitates the setting of four switching
times per day; each switching time can be assigned a fan switch position (off, speed I,
or speed II) and a setpoint pair (Economy and Comfort); the settings are made on
operating level 3.
•
Summer- / wintertime changeover
This function prevents freeze-up of the hot water heating coil at low outside
temperatures (especially in plants that use on/off dampers).
The period of time during which preheating is active can be adjusted from 0 s to 10 min.
When the plant is switched on, only the hot water circulator (Q13 / Q14) initially is
activated while the hot water valve (Y10) is fully open.
Anti-icing protection for
HR equipment
Efficiency supervision
of the heat recovery
system
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Start-up mode
Control
Switching the plant via
control inputs E7 and E8
Timer
Preheating time
