Check through the manual, If I remember WB recommend a system filter is fitted, that being said the system must be flushed and cleaned as part of the installation process.
It will only become a problem if there is a warranty call and the engineer comes along and checks the system water, if it's full of crap then that'll be how good the warranty will be. Maybe worth a shout to the installer, who manages the grant, was that through the installer company?