You need to get the original installers back to sort for you.
As mentioned above sounds more like air in the system or pump speed set to high.
You have not said if you have the boiler installation benchmark certificate filled in or checked if the boiler is registered so worth you checking these things,
cheers,
Andy
As mentioned above sounds more like air in the system or pump speed set to high.
You have not said if you have the boiler installation benchmark certificate filled in or checked if the boiler is registered so worth you checking these things,
cheers,
Andy