hi i had a small double rad in kitchen which did not work. Pipes would get warm but rad freezing. Having kitchen rejigged so decided to replace faulty double rad with a longer single rad. I shut of all water supplies, drained the rad, carried out the required cutting and shutting of pipes etc then turned the water supply back on. I assumed i would have to at least bleed that rad if not the rest of them too. When i turn on the central heating now it proceeds to trip out after approx 3 mins or so. I then have to carry out full reset to get it to work again. It comes back on but carrys on to do same again. The boiler and heating make some crazy noises. There is obviulsy a bad air lock which i was expecting but how the hell do i get rid of it.?? Iv tried bleeding the kitchen rad but after getting some air out now and again i dont get any water. Ive checked other rads and the other 2 downstairs rads have water but all the upstairs dont bleed any air or water?? I noticed the pump waas getting very hot, i assume its due to having no steady flow of water going thru so i keep turning it off for long periods. Iv tried venting the pump but doesnt seem to do anything, no air comes out and no water. Only thing left is a large bleed valve on a pipe in front of tank in airing cupboard. Would i need to bleed it here? the valve is larger than a rad bleed key and i dont have one to fit it. My boiler is a baxi solo 2 rs. Am i missing something obvious here or could i have a blockage or something? seems strange im not getting any water at upstairs rads. Help much appreciated!!!! thanks in advance