The upstairs radiators hardly get warm. The obvious solution is to bleed them but none of them have a bleed valve. The downstairs radiators have a 'y' shaped valve on what I think is the feed pipe(?). Do I have to have the whole system drained?
There'll be bleed valves on the radiators, they will be at top left or right hand side. Either on the side of the radiator, or on the back of the radiator panel. Some are covered with small white plastic caps.
Turn off heating to bleed the radiators, and bleed until water appears. You may need a cloth to catch abit water.