No flow in CH flow pipe

I have a cold radiator in the house we have moved into. I suspected the rad might be blocked or the TRV stuck so isolated it and flushed it through but that wasnt the problem - there was no water coming out of the flow pipe to the rad (I took the TRV off and no water came out). The rad is downstairs, the pipes that feed it are plastic with pushfit connectors (look quite old) and go up the corner of the room into the bedroom floor above but unfortunately the room has a laminate floor.

I have had the corner of the laminate up and can see the pipes coming up but they dont connect near the closest rad in that room and cannot see where they go without ripping up the whole floor. Is it likely to be a blockage in this pipe somewhere? Wouldnt the pressure in the system be enough to blow out any debris in the pipe? The only other thing I can think is there is a valve somewhere on that pipe that is closed but why would that be closed??

Edit: its a sealed system running about 1.5 Bar if that makes any difference

Sound like the rad isn't connect to your system if there is no flow of water from the flow or return pipe work.

When you removed the rad to flush it out was there any water present?

the radiator was full of water when I disconnected it, and water does come out of the return pipe when that is disconnected (I am assuming here that flow is on the TRV end and the return is on the lockshield end but guess that might not be the case). As the system is pressurised then the rad will still fill up with the flow pipe blocked

Did the pipe leading up to the TRV get hot?

Did you check the pin on the TRV moved up and down?

When you say you removed the TRV did you mean the whole valve or just the head?

Try turning off the rest of the radiators to see if you can force a potential blockage through.

I might try turning off all the others to see if that helps. The radiator itself is now lovely and clean inside - quite a bit of black water came out when flushed with the hose pipe but not really thick sludgy stuff.

I actually took the TRV off the flow pipe and nothing came out of the open pipe end. Water did come out of the return pipe when I unscrewed that below the lockshield vlave

It sounds like its been blocked for ages...try the old magnet against the pipe trick to see if there's any attraction (usually on a bend).
Looks like you'll need to do some pipe replacement, I guess.
John

you could also try using a wet and vacuum to suck water thro' the pipe, it is either a blockage or an air lock, I favor an air lock, that will need sucking with some force.