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9.4.5. Filter supervision
CADB/T-HE BASIC heat recovery units are supplied with pressure switches mounted on both fi lters
(supply and extraction). When the differential pressure value measured by the pressure switches exce-
eds 200Pa an alarm is produced. Depending on the particularities of the installation (operating hours
and polution of the outdoor environment) it may be advisable to change the pressure switch setting as
indicated in the following table:
Filters state
Airfl ow
Action
The fi lters alarm appears offen
When the dirty fi lter alarm is active,
the air fl ow is correct
Increase pressure switch setting to
300 Pa
No dirty fi lter alarm appears or it
takes too long to appear.
Insuffi cient air fl ow due to fi lter
clogging
Reduce the pressure switch setting
to less than 200Pa
The fi lters alarm appears with too
much frequency
When the dirty fi lter alarm is active,
the airfl ow is insuffi cient
The performance of the heat
recovery unit is not enough:
- Review the dimensioning of the
duct system
- Check leakages
- Oversize the selected heat recovery
unit
To change the pressure switch setting, follow the sequence below:
1. Access the fi lter zone in which the
pressure swich fi lters are placed
2. Lift the pressure switch cover
H
2
O
base
lift slightly and remove
the dissasembly the cover
from the base
3. Turn the dial (1) using a fl athead
screwdriver, until the pointer (2)
indicates the pressure value to be
defi ned
9.4.6. Fan status monitoring
After two minutes from the fans run order, the controller verifi es the operation of both fans (supply and
extract). In case of detecting an abnormal operation of any of them, the alarm LED will light, and the unit
stop sequence will be performed.
The fan status detection is done in two different ways depending on the type of motor used:
• In fans of lower power, it’s done by the supervision of the RPM’s.
• In fans of higher power, detection is done through the alarm relay integrated in the motors electronic
PCB.
