I have just installed a heated towel rail for an existing radiator linked into my central heating system. To do this, I drained the system, did the job including moving the rad valves and extra pipework, refilled the small header tank (with Fernox and water), bleed the rads starting from the top ones. I felt quite pleased with myself until the hot water did not heat up.
The hot water tank is in the loft below the 2 filler tanks and is heated indirectly via one of two motorised valves and and a pump. The other valve is for the central heating system. The valves and the pump appear to be working.
In draining the system have I generated air pockets that will not allow the flow of water around the pump, valves or THE BOILER. If so, how do I clear it?