I've just drilled through a pipe under the floorboards :-( It's one of the 22mm pipes between the condensing (not combi) boiler and the hot water cistern. I've fixed it and bled (bleeded?) the pump. The boiler starts normally but then goes off after about a minute without heating the water.
I'm assuming water is coming from the loft header tank because air and then black water came out of the pump when I bled it. There isn't any air in the upstairs radiators.
Any ideas?