TAC AB, 1998-10-23 0-004-7614-0 (GB), 7:11 (24)
TAC 2413 Handbook Functional description
The exhaust air sensor is also used as a limitation sensor to pre-
vent freezing of the HEX. A separate controller monitors the tem-
perature compared to the value of P 38 and will limit the output
signal to the heat exchanger if there is a risk of freezing. If there
is no sensor, the function is not available, and the parameter is not
shown.
If the sensor is available, but no limitation is desired, the limit is to
be set to its minimum level, P 38.
There may be freezing in heat exchangers, which will have effect
on the efficiency of the recovery AHU. For this reason, TAC
2413 has a built-in defrosting function which is activated by
short-circuiting the exhaust air sensor with the differential pressu-
re sensor. The signal of the HEX is controlled towards its closed
position using a separate controller.
This controller strives for holding the minimum supply air temperatu-
re, while the main controller continues to control the heating valve ac-
cording to the normal setpoint. This means that the defrosting status
will depend on the capacity of the heating coil.
If the defrosting is not stopped within an adjustable time, which is fac-
tory set to 10 minutes (0=no stopping of TF), TF is stopped in order to
quicken the process. When the pressure sensor is released, the defros-
ting continues for another three minutes before being stopped. An
alarm is tripped if the defrosting has not stopped within the “Maxi-
mum allowed defrosting time, which factory set to 30 minutes. Please
refer to the section on alarms.
P No. Parameter Min. Max. Factory set. Change Comment
P 05 Return air temperature Measured value
P 07 HEX efficiency (%) Measured value
P 08 Exhaust air temperature Measured value
P 10 Heating setpoint 0 °C 50 °C 20 °C
P 18 Output signal to HEX (%)
P 38 Setpoint at min. temp., HEX –20 °C 10 °C –3 °C
P 39 P band, defrosting 1 °C 200 °C 50 °C
controller for HEX
P 40 I time, defrosting cont., HEX 1 min 60 min 8 min
P 41 Time to TF stop, 0 min 30 min 10 min 0=supply fan is not stopped
rapid defrosting
P 42 Max. allowed 0 min 60 min 30 min (will trip an A alarm
defrosting time if it is exceeded)
P 58 P band, supply air controller 1 °C 100 °C 25 °C
during HEX control
P 59 I time, supply air controller 1 min 20 min 4 min
during HEX control
T (return air) – T (exhaust air)
T (return air) – T (outdoor air)
η = x 100 = (%)
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