Cold Radiator

[phoenixx235]

One of my radiators doesn't warm up. Checked the pin on the thermostat, flushed the radiator in case of sludge. I bled all of my radiators and turned them off, apart from the one in question.

The inlet pipe gets very slightly warm, the outlet pipe is very cold. When I disconnected the plastic outlet pipe, water gushed from the pipe (a large bowl's worth). The water was filled with lots of black particles. When I disconnected the plastic inlet pipe, there was a constant dripping of water from the pipe. The water that dripped from inlet pipe was noticeably clearer than from the outlet. This was with the radiators valves set to off, so no water came out from the radiator. I used a small flexible wire to to and clear any blockage in both pipes, but nothing was there within the 10" I could reach.

I have emptied and flushed the radiator, when I reconnect I can hear it refilling, so I know at least the inlet is clear. When I drained the radiator, I disconnected both pipes. I opened the valve on left (outlet), no water came out from radiator at all. I opened the right valve (inlet), the water came out.

Could the problem be due to a kinked pipe on the outlet (or a clogged outlet pipe) or a defective valve on the outlet?

 

[Gouldy]

Sounds like a blocked pipe, what size is the pipework? Micro-bore?

 

[phoenixx235]

The pipes that come out of the wall are 10mm (outer diameter), grey plastic pipes.

 

[Best]

Agree with Gouldy that it is a blockage in the pipe if you disconnected the pipe from the valve and little flow through it.
Might be helpful to flush water through the pipe, reversing the flow direction. Mains water pressure can be used carefully by a professional.

 

[Gouldy]

Yeah, may be blocked further up the pipe/at the manifold. Went to a similar call out last month and managed to shift a few blockages by removing radiator and attaching pressure tester to rad valve and forcing flow to reverse (risky as push fit fittings may "pop"). Couldn't shift them all though, so customer has asked us to re-pipe system in copper. From my experience this issue is common with the grey plastic pipe circa 20 yrs old as a lot of it is un-barriered.

 

[phoenixx235]

Thanks for your replies!
I've been testing the other radiators individually, there's another upstairs with an identical issue, and also one downstairs.
Is there anything I can try myself that may help, I don't have much spare cash at the moment (we replaced the boiler this winter, the system itself was put in in 2004). Would any chemicals such as Fernox F5 help?
What kind of cost would I be looking at for clearing the blockage or changing the pipes?

 

[Best]

I would try to get some flow through the pipe first, before you try any chemicals.

 

[ignite 247]

switch all radiators off in property apart from that one and tap with mallet with boiler on high temprature, usually always sorts it for me 🙂

 

[SavageW]

Definitely going to be blocked on the microbore manifold by sounds of it, you could try chemical through system but you may need a heating engineer ideally to have a look