The3rd Earl Of Derby wrote:



open the bypass valve somewhere on the piping below the boiler,its a black
knob? turn the valve to the open position for 10mins and then close it
again.

--
Sir Benjamin Middlethwaite

Some boilers dont now use a 'filling loop' which is what you mean. They
have a built in filling system that usually requires a key that the
installer usually leaves. Get the Boiler Manual from the maker and it
will tell you how to top up the pressure.