Blockage in CH pipe?

[WaterTight]

Customer said rad not getting hot.

Had a look. Pipe red hot up to TRV but rest of rad luke warm. Heating had been on about an hour.

So changed TRV as usually is that. Same problem. Disconnected TRV from rad and opened it up into a tub. Flow but very weak. So suspect something reducing flow in pipe. All other rads including some quite nearby working. Pipework all under floor/boards/carpet so left it at that for that visit.

He isn't certain how long it's been an issue. He knows the TRV was changed a few years ago but not certain if it worked or not. Said few mild winters, he can't be sure whether he'd have noticed. But he said before that he is sure it worked at some point and no work done to rad/pipes nearby in a long time (other than the previous TRV change.)

Before lifting boards are there any clever quick tricks you can try like a wet vac on the pipe or something? It's vented set up, F+E in loft, whole system looks well installed/looked after but I could tell the pipe goes into push fit when goes under floor.

Thanks

 

[ShaunCorbs]

You could put mains through it or pump it up to a couple of bar with a pump

 

[Scott_D]

Pressure test pump but might not work if it lets a little pressure through

 

[WaterTight]

Cheers. Could it be anything other than a blockage/restriction in the pipe?.... I'm guessing not?

 

[ShaunCorbs]

F and e tank full and fills when you drain another rad ?

 

[WaterTight]

It was full. Not drained anything. Bunged it to change TRV.
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If I drained another rad and it didn't refill.....what would that mean?

 

[ShaunCorbs]

It was full. Not drained anything. Bunged it to change TRV.
[automerge]1601491468[/automerge]
If I drained another rad and it didn't refill...what would that mean?

feed could be blocked or f and e dry hence the low flow

 

[Ben-gee]

I had a similar one , it was last rad on system and the 15mm return back to the main 22 return was basically solid with sludge. All other rads worked fine.
It was old brown Acorn pipe so I could undo fittings and remove it, about six foot long and I could not clear it - even took it to a garage next door to use their compressed air gun!
I just replaced the pipe and fittings and everything worked as it should- I expect it will block again but not for another 25 years.

 

[king of pipes]

If I have a vented system choked up badly I isolate the mains into the Fe tank wet vac the tank out disconnect it and put it to one side , cap the vent connect the mains to the cold feed with hep 2o with a lever valve inline, lock open the heating zone valve, connect a hose to the blocked pipe securely and run to external drain, you can then flush the pipework from above its a ballache to do but does work, you can isolate the rads one by one and flush the debris out and any sludge, a cleaning chemical sentinel x400 or similar added to the system a week or so prior to this will also help break down the sludge allow a whole day to do this . Regards Kop