Another CH problem

Hi, hope you can help ahead of calling BG out for a visit

Central heat is working, but only heats for a short time before store temp dips below 60.

Heating shuts off while boiler catches up. Boiler is old Myson Apollo 30B.

This seems to be a recent problem and may be linked to new rad in loft added by splitting CH circuit at the Boilermate outlet or scale in the boiler if the installers did not add inhibitor.

Boilermate does heat to 77, so either the pull on the store is too great or the boiler has a flow problem.

Any ideas from fellow users?