Exhaust Air Fan Control According To The Supply Air Fan; Control Of Dampers; Recirculation Based On Supply Air Temperature; Full Recirculation Function - Salda MCB Technical Manual

5.33.7. EXHAUST AIR FAN CONTROL ACCORDING TO THE SUPPLY AIR FAN

This function can be activate in the column SERVICE › FANS. When this function is active, only the percentage/pressure/quantity of the supply air flow
are indicated. The exhaust air flow is controlled automatically by maintaining the nominal relation of the air flows. This function requires pressure
transducers, which measure the supply air and exhaust air flows. If MCB inputs are not sufficient, it is possible to use the pressure converters
through Modbus communication line. The supply air fan can be controlled by percentage, according to the pressure or flow, while the exhaust air
fan is always controlled according to the flow.

5.34. CONTROL OF DAMPERS

The following can be connected to the system:
› supply air damper (ON/OFF, 3P, OPEN/CLOSE or Spring-return type). It is open to before starting the supply air fan and closed when it is
stopped;
› exhaust air damper (ON/OFF, 3P, OPEN/CLOSE or Spring-return type). It is opened before start-up of the exhaust air fan and closed when
it is stopped;
› recirculation dampers which are used to protect the heat exchanger from freezing, to maintain temperature and for complete recirculation
function;
› Fire dampers with one or two limit switches. They are controlled in the same way as supply/exhaust dampers, except for cases when testing
function is active or fire protection is activated.
If ON/OFF, 3P or OPEN/CLOSE type damper is indicated, proper opening time must be indicated. ON/OFF type damper control:
› When it is necessary to open, OPEN signal is activated;
› It is necessary to wait until it opens and fans are started;
› OPEN signal is activated during the entire operation time;
› When shutting down the system, it is necessary to wait for 10 s, until the fans stop rotating and switch off the OPEN signal.
3P type damper control:
› When it is necessary to open, OPEN signal is activated;
› Waiting until it opens, OPEN signal is switched off and fans are started;
› OPEN and CLOSE signals are switched off during the entire operation time;
› When shutting down the system, it is necessary to wait for 10 s, until the fans stop rotating and activate the CLOSE signal for an indicated
time period.
OPEN/CLOSE type damper control:
› When it is necessary to open, OPEN and CLOSE signals are activated;
› It is necessary to wait until it opens and fans are started;
› OPEN and CLOSE signals are activated during the entire operation time;
› When shutting down the system, it is necessary to wait for 10 s, until the fans stop rotating and switch off the OPEN signal (CLOSE remains
active) for an indicated time period.
Spring-return type control (with a spring)
› When opening is required, the OPEN signal is activated;
› wait until it opens, and the fans are activated;
› OPEN signal is on full-time during operation;
› when the system is being stopped, wait for 10 seconds until the fans stop, and the OPEN signal is deactivated, the dampers close immedi-
ately.

5.34.1. RECIRCULATION BASED ON SUPPLY AIR TEMPERATURE

This function is designed to maintain the supply air temperature by reducing the volume of unfavorable fresh (outdoor) air. Additionally it is recom-
mended to use CO sensor for the premises air, whereas upon increase of CO
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Temperature maintaining is controlled only when the heat exchanger operates at full capacity.
Function is switched on/off in the SERVICE › DAMPERS window RECIRCULATION BY SUPPLY. It is necessary to indicate PID coefficients in the window
ADJUSTER › PID CONTROLLERS ADJUSTING.

5.34.2. FULL RECIRCULATION FUNCTION

This function is designed to save consumption of heating energy, by recirculating only the premises air. It is used only when fresh air is not nec-
essary. During operation of recirculation damper control and ECONOMY and BUILDING PROTECTION modes, there is a possibility to switch on a full
recirculation function.
During this time the recirculation damper is opened and outdoor air damper is closed, exhausted air fan is shut down and the heater maintains
the indicated supply air temperature.

5.34.3. OUTDOOR AND SUPPLY AIR RECIRCULATION DAMPERS

If only recirculation damper of supplied air is activated, then it alone shall perform all recirculation functions. If both (outdoor and supply air) recir-
culation dampers are activated, then their functionality shall be distributed as follows:
The supply air recirculation dampers shall perform the following:
› Full recirculation function;
› Supply air temperature control;
› Shut down of exhausted air fan, when recirculation takes more than 80 %;
› CO reduction is performed by both dampers.
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MCB_miniMCB v2019.1
the closing level of recirculation damper would be limited.
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EN | 13