I have removed a radiator in up stairs bath room to re tile, this involved draining lots of water from the system. I have fitted two new values for a new rad. In the meantime I now have cold radiators, the heating is back on, the pump is pumping and the heating tank has water. also I notice the bottom valve on a down stairs rad lets no water out when released? Only a couple of the microbore pipes in the house feel warm. Have tried to bled rads and no joy. HELP