Vertical rad bottom pipe is toast, rest is cold

[Onetap]

Check for air locking as above.

Then shut down one radiator valve completely. Open it gradually, 1/2 turn at a time or so until you feel hot water entering the radiator. See if it heats the top of the rad like that, instead of just the bottom as previously.

 

[adlplumbing]

just so can get this right the whole length of pipe is hot on flow side
is hot on the return side?
and the pipes that run in between like rung`s on ladders are cold
if this right try this
turn water off to rad
take rad off wall after draining the water out
blow down it and see if you can feel blockage or restiance in the pipe work stoping the flow water round the rad

 

[infodude]

just so can get this right the whole length of pipe is hot on flow side
is hot on the return side?
and the pipes that run in between like rung`s on ladders are cold
if this right try this
turn water off to rad
take rad off wall after draining the water out
blow down it and see if you can feel blockage or restiance in the pipe work stoping the flow water round the rad

Hot on flow side, yes. Hot on return side - check.
"Ladder" is lying on its side. Bottom is hot, rungs and top are cold.

I have removed rad from circuit, it has constrictions inside bottom pipe as expected.

Put plastic hose in its place so I can see the flow. It is truly bad.

I need to fix that, but first I'd like to say thanks to all. You've really been great

-Phil