So if you turn all upstairs off no flow to downstairs?
Yep, no heat to downstairs with all upstairs off. But plenty of flow through all rads, both sides/valves when flushed.
Discuss Central Heating - Blocked 22mm return pipe? in the UK Plumbing Forum | Plumbing Advice area at PlumbersForums.net
So if you turn all upstairs off no flow to downstairs?
I'll leave you and Shaun to discuss flow as you seem to be getting somewhere and I don't want to interfere when it's going well.
Re the tees on the return mystery, I've thought about that. Obviously the return from the cylinder and the radiators will join up at some point before they reach the boiler so quite possible that the tees into the return from the cylinder are from radiators or from a bypass valve.
When you tested / flushed did you turn all the other rads off and then see if water came out of both sides ?
Nowhere here can I see any mention of removing pump head and checking/cleaning veins.
That would have been first on my list.
Reply to Central Heating - Blocked 22mm return pipe? in the UK Plumbing Forum | Plumbing Advice area at PlumbersForums.net
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