Protection From To High Condensate Level; Indication Of Bypass Damper Fault - Salda MCB Technical Manual

› Specified exhaust air temperature difference compared to the calculated freezing temperature (this temperature is calculated according to
the outdoor air temperature, room air temperature and humidity);
› According to the pressure switch.
Possible protection measures (to be carried out one by one as specified):
› Recirculation of outdoor and exhaust air;
› Opening of the bypass damper or control of the segment valve, or slowing-down of the rotor;
› Heating of outdoor air using a
› Suspension of the supply air flow or reduction of the flow based on the set exhaust air temperature;
› Shutting-down of the unit according to the low supply air temperature (by default, the limit is 5 °C);
› Shutting-down of the unit if there are no protection measures activated (shut-down after 5
› Shutting-down of the unit due to failure to reach the safe zone corresponding time interval (two cycles, by default, 60 minutes);
› Shutting-down of the unit according to the critical outdoor air temperature (to be shut down after 60 seconds).
The protection activation conditions and protection measures can be activate selectively. The protections are active only when the outdoor air
temperature drops below the set limit, i.e. the protections will respond to the pressure switch only when the outdoor air temperature drops below
the permissible limit. For the anti-frost protection, the time interval after which the system switches from one protection measure to another is
also specified (by default, it is 30 minutes). If at least one of the activation conditions is satisfied, the protection becomes active and a message
is shown. The initial protection is recirculation, which is followed by the bypass damper or segment valve, then preheater and then, if the power is
not sufficient, the supply air flow is suspended. If the protection does not help within the specified time interval (by default, 30 minutes), the system
switches to the following one. The protections are switched from one to another in accordance with the sequence.
The recirculation of outdoor and exhaust air is an effective and cost-saving protection but it supplies exhaust air back to the supply air flow.
When using the bypass damper or segment valves, the supply air heater must be connected. By slightly opening the damper, the cold air flow
through the heat exchanger is reduced but supply air is cooled and must be heated using the supply air heater. This protection slowly opens the
bypass damper as long as the activation conditions are satisfied. When suitable conditions are reached, the damper is stopped for 5 minutes and
then it is slowly closed. If the outdoor air temperature drops below the permissible level (the heating power is not sufficient), then the damper is
forcedly closed according to the supply air temperature.
The bypass valve can also be with segment valves. In this case, the supply air temperature drops less than when using only the bypass damper.
At the time of deicing, segments are closed one by one in sequence, i.e. only one segment can be closed at a time and the bypass damper is
opened. If at least one segment is closed, then the bypass damper is opened; if all the segments are opened, then the bypass damper is closed.
For the protection with the preheater, the position of the outdoor air sensor in respect of the preheater is specified (upstream/downstream). If the
sensor is upstream the preheater, then the unit is not shut down if the required outdoor air temperature is not reached. At the beginning, the out-
door air preheater is activated to the full capacity for a certain period of time, and that it begins maintaining the specified deactivation temperature
(outdoor or exhaust air temperature).
If the preheater capacity is not sufficient and the supply air flow reduction is permitted, then the supply air fan is periodically shut down and the
heat exchanger is deiced by heating it with exhaust air. When the fan stops, the supply air damper is closed.
Recirculation, the bypass damper and supply air flow suspension operate in periodic cycles. The minimum deicing time is 5 minutes, and the
minimum time interval between deicing cycles changes depending on the outdoor air temperature (see the diagram), i.e. the lower the outdoor air
temperature is, the shorter the time interval between deicing cycles. The exhaust air temperature and the pressure switch of the heat exchanger
can extend time intervals between deicing cycles and to extend the deicing time, i.e. if the minimum time interval after a deicing cycle has elapsed
and the pressure valve has not yet been activated, then its activation is awaited; otherwise, if the required conditions are not achieved within
5 minutes during deicing (the pressure valve does not reset or the exhaust air temperature does not increase), then deicing is extended. If the
protections according to the pressure switch and/or according to the exhaust air temperature are not activated, then deicing cycles take place at
minimum intervals.
The dependence of the minimum time interval between deicing cycles (minutes) on the outdoor air temperature.

5.35.3. PROTECTION FROM TO HIGH CONDENSATE LEVEL

If there's too much condensate, the condensate pump transmit signal to MCB board. The user receives warning immediately. If the signal is active
for more than 60 min, airflow will be reduced till minimum. The protection will be disabled automatically after the signal discontinues.

5.35.4. INDICATION OF BYPASS DAMPER FAULT

This function is intended to monitor the operation of the bypass damper (operated by a stepper motor) and only starts functioning after successful
calibration.
The closed damper must necessarily push the end position switch, which must disconnect when it opens by more than 25 %. When the damper
is not operating correctly, a fault message is displayed.
MCB_miniMCB v2019.1
preheater;
35 min. 30 min. 25 min. 20 min.
minutes);
15 min. 10 min. 5 min. min.
C
o
-2 C
o
-4 C
o
-6 C
o
-8 C
o
-10 C
o
-12 C
o
-14 C
o
-16 C
o
-18 o C
-20 C
o
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