While you wait for answers, we may have found some information which could help you.
Success
Message
DHW running hot then cold?
what part do ineed?
how can i fix this ?
falling presher?
2 amp fuse blown?
DHW Run's hot and then goes cold?
shower in bathroom keeps going hot then cold then hot etc?
Can't get hot water but central heating is working fine, any ideas??
c/h hotwater?
ferolli modena 102?
Ferroli Boiler Optimax HE 31C?
High pressure on my Optima Ferolli 901 central heating?