Boiler filling loop will not fill!

On the filling loop do you have two thumb like taps you may be opening one that is on main but not opening the one to the boiler. Also if not thumb turns They may be isolation valves and yiu need to open these at a horizontal position to open them up

Hi, The lever valves on your isolation valves may be broken internally. If you hear an initial water sound which stops very quick, there is an obstruction. It could be a faulty non-return valve (Internal of the filling loop, normally on the heating size to prevent heating system water mixing with mains pressure) or as said above, a broken lever. I would advise you to replace the whole filling loop if you feel confident. Please remember to drain your heating system and isolate mains pressure. If you may struggle with this, I would advise to get a qualified Plumber/Gas Engineer to carry out the works. As an estimation, you are looking 1 hours labor @ £60-£80 plus materials. I hope this helps! Matt @ Plumb Assist

Sometimes the lever can be defective and does not turn the valve, this can be removed by taking the screw out,and the valve can be turned with a spanner or wrench

You should have 2 blue lever valves on the underside of the boiler. 1 on your cold mains inlet and 1 on the front of the return valve of the boiler. Both blue levers need to be in the horizontal position to enable filling. But do thus very slowly to make sure you don't over pressurise the CH. Once filled to between 1 and 1.5bar, turn both blue levers back to the vertical position