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Reco-Boxx ZXR / ZXA / Flat – Operation and maintenance instructions
[03/
2022 ]
9.18 Type 18: Alarm indicating an incorrect position of the modulating bypass relative to
the ordered position
• Conditions:
• PX units with modulating bypass.
• Causes:
• This alarm indicates that the modulating bypass has not reached the ordered position within
10 seconds. The most common reason for this is a damaged position sensor on the bypass actu-
ator, and this must be replaced. Other reasons may be that the control board output is damaged,
implying the replacement of the board, or a mechanical blocking verified by a visual inspection of
the bypass.
• Effects:
Displayed on Touchpanel
Code
Text displayed
Level
B.20
Position of the modulating bypass incorrect
3
TAC control board
ALARM OUTPUT
AL dPa OUTPUT
LED ALARM
Fans
Alarm Status
/
ON
stopped
Manual reset mandatory.
Diagnostic:
Stop the unit, do an alarm reset, check and eventually correct actuator wiring to the control board and
then check that the bypass can move physically: connect IN3 to +12V to force the bypass to open.
• If the bypass stays in close position, check if there is some mechanical obstruction that makes the
actuator stuck, otherwise:
• Either the actuator must be replaced.
• Or the control board must be replaced.
• If the bypass opens completely:
• Do several Close/open cycle using IN3 to try to reproduce the alarm and check bypass position in
info menu. If the problem cannot be reproduced, try with fans boosting.
• Either the actuator must be replaced.
• Or the control board must be replaced.