That's great Ken, one picture is worth a thousand words.
From your post #80
All Rads ON 0.6m3/hr 34W
Large T.Rad Hot
Small T.rad Hot
Back B.room Hot
Front B.room L.warm
Entrance Cold
Sitting Room Cold
Kitchen Just Off Cold
Small T.rad Off, remaining Rads ON 0.4m3/hr 32W
Large T.Rad Hot
Small T.rad Off
Back B.room Hot
Front B.room L.warm
Entrance Cold
Sitting Room Cold
Kitchen Just Off Cold
Bothl T.rads Off, remaining Rads ON 0.0m3/hr 22W
Large T.Rad Off
Small T.rad Off
Back B.room warming up
Front B.room warming up
Entrance Cold
Sitting Room just about warming up
Kitchen Just about warming up
What strikes me straight away is the back bedroom, It stays Hot in the first two cases and is heating up with both T.rads off but with apparently no pump flow.
If its getting hot then that sort of proves that there is a flow through the main flow/return circuits? Can you try that Back B.room rad on only and see the pump values, if any?,
Are you sure that the isol valves on the 3 "cold" rads, Kitchen, Entrance and sitting room, are fully opened?
Flushing everywhere you can with the mains is about the most logical step now.
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