there are TWO types of filling loops on combi boilers
INTERNAL BUILT IN filling loops [normally under the boiler]
and EXTERNAL filling loop valves [normally 2 valves protruding from the boiler pipework connected by a silver flexible pipe]
which one do you have?
just need the
MAKE of boiler [e.g Worcester/vaillant/baxi/ideal/etc]
MODEL of boiler [e.g. Worcester GREENSTAR/ baxi DUOTEC/ vaillant ECOTEC/ ideal LOGIC/ etc]
and GAS COUNCIL NUMBER for your boiler [which is normally on the front cover of the boiler BOOK/MANUAL which you hopefully have to hand]
I can then direct you to the specific manufacturers youtube website on how to top up the pressuere on your boiler
now which boiler do you have?
Q, May 2015