Vaillant Vantage 120 Installation Instructions Manual page 35

Fault D:
Deteriorating water pressure and flow
from hot water terminal fittings.
Check incoming main water pressure.
Check line strainer
(in pressure limiting valve).
Check pressure limiting valve.
Check sytem for blockage.
Symptoms still persisting?
Check system as for discharge from
temperature or expansion relief valve.
Fig. 19
Vaillant Vantage 120/150/200
Poor
OK
Dirty
OK
Faulty
OK
Blocked
OK
NO
YES
Inform customer to have water service
checked by water undertaker.
Clean / replace strainer.
Replace faulty valve.
Replace / clear blocked components.
Fault remedied.
Fault finding 11
35