While I was topping up my combi-boiler as the pressure had fallen, the blue plastic 'tap' under the boiler broke off (before I managed to turn it on, thankfully). It broke in two and came away from the screw which controls the flow. It rarely needs topping up but not sure what I will do next time I need to - not sure how another plastic tap could be attached onto it, so any suggestions - is this going to be an expensive repair.
As a matter of interest, what would have happened if it had broken off when it was 'on'?
Thanks
Alex