F.075
The pressure change is too low when the heating pump is started up.
Vaillant ecoTEC Plus Combi
Possible cause
Water pressure sensor defective
Measure
Check and, if required, replace the water pressure sensor.
Possible cause
Internal heating pump defective
Measure
Replace the internal heating pump.
Possible cause
System pressure too low
Measure
Check the system pressure.
Possible cause
Internal expansion vessel defective
Measure
Check and, if required, replace the internal expansion vessel.
Possible cause
Insufficient/no water in the product.
Measure
1. Fill the heating installation.
2. Check the product and the system for leakages.
Possible cause
Air in the product
Measure
Purge the heating installation.