Vaillant ecoFIT pure Series Installation And Maintenance Instructions Manual page 44

Code Meaning
F.75 Fault: No pressure change detection when start-
ing pump
F.76 Overheating protection on primary heat ex-
changer has responded
F.77 Fault: Flue non-return flap/condensate pump
F.83 Fault: Flow and/or return temperature sensor
temperature change
F.84 Fault: Temperature difference at the flow and
return temperature sensors
F.85 Fault: Flow and return temperature sensors
incorrectly installed
F.87 Ignition transformer not connected
F.88 Gas valve not connected
F.89 Incorrect pump detected
con No communication with the PCB
44
Cause
Water pressure sensor and/or pump defective, air in the heating installa-
tion, insufficient water in the product; check adjustable bypass, connect
external expansion vessel to the return
Cable or cable connections for safety fuse in primary heat exchanger or
primary heat exchanger defective
No response from flue non-return flap or condensate pump defective
When the burner starts, the temperature change registered at the flow
and/or return temperature sensor is non-existent or too small.
–
Insufficient water in product
–
Flow or return temperature sensor not in correct position at pipe
The temperature sensors return implausible values (temperature differ-
ence < -6 K).
–
Flow and return temperature sensors are inverted
–
Flow and/or return temperature sensors installed incorrectly
The flow and/or return temperature sensors have been installed on the
same pipe/incorrect pipe
Ignition transformer plug not plugged in or has come loose, multiple
plug on the PCB not plugged in correctly, interruption in cable harness,
electronics defective
Gas valve plug not plugged in or has come loose, multiple plug on the
PCB not plugged in correctly, interruption in cable harness, electronics
defective
Unsuitable pump connected, PWM plug not plugged in or has come
loose, multiple plug on the PCB not plugged in correctly, interruption in
cable harness, electronics defective
Communication fault between the display and the PCB in the electronics
box
Installation and maintenance instructions ecoFIT pure 0020230535_07