Sorry when I say virtually closed I mean it's just cracked a tiny bit so a 1/16 of a turn maybe and that's on all of them bar the kitchen and they are all still hot. Flow on kitchen rads now to up high 50s with return being 12 to 15 degrees lower. Doesn't seem excessively cooler but don't think I can close other lockshields any further without shutting off the radiators. Maybe I can sneak the towel radiators a little more as they seem to have a massive impact on the whole system even being only a tiny bit open on the flow and return.
Hi all, bit of an update, while poking around in the cupboard with the cylinder and valves I noticed a gate type bypass valve above the cylinder return pipe and before the 2 port motorised valves which was fully open. In other words a large proportion of flow from the boiler would have been going through the pump and then straight back to the boiler as the path of least resistance while only some would have gone through the motorised valve to the rads. I've shut this now bar the last 1/4 turn and my rads have never been hotter, they are hotter now than the fires of hell. I suppose I have some more balancing to do!
Ok so pump most definitely does not like that valve being closed. Must be required for pump overrun. Have closed it 3/4 a turn now, looks like I'll have to play tunes on this Vs balancing radiators. I knew it was too easy!