Cold Radiator

[David]

I've got a radiator that is not getting hot. It has been bled. Its got a TRV type control which shows a number as it is turned. Removing the TRV revealed a pin, checking a working radiator, this pin is raised and can be pushed down. However on the faulty one, the pin was not raised and removing the black fixing nut, the pin could be pulled out. I would have expected water to come out as I assumed it was the water pressure that kept the pin in the raised position. Is this correct or is there a blockage in the pipes?

David

[Huge]

The pin operates a valve, which is presently seized onto its seat. It is closed by pressure from the thermostat head, and opened by a (very small) spring.

You can free them up by pushing the pin in and out with a pair of pliers, but in the long run the only solution is to replace the TRV.

They seem to have a life of about 20 years, judging by the steady succession of mine that are having to be replaced for this reason.

[Andy Hall]

The pin is held up with a big spring. You should have a movement of about 3-5mm as you described.

I would suspect that the valve is broken or there is a foreign body in it. Note that the movement is small.

You will have to drain the system and take it off to see. There may be sludging as well and you will be able to find that out as well. You can make an educated guess about this by feeling the centre lower area of other radiators. If they are cool then there is probably sludge. A search in Google Groups for recent posts will show you some ways to deal with this.

Ob_SWMBO_Health_Warning: Remember that water in heating systems and sludge are indellible dyes for carpets........

If the system is reasonably clean, you could consider putting in a flushing agent and running the system hot for a few days. Then drain, flush and fill with corrosion inhibitor. £40 or so in chemicals is pretty cheap insurance considering the damage that ensues in unprotected systems..,.....

.andy

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[David]

Thanks, both, for that. Poked something in the hole but nothing happened, so it looks like a replacement job.

I have BG's Central Heating Care (I know some people don't think that's wise, but anyway), would this be covered? I've got the annual boiler inspection due soon.

David

[BillR]

Try banging the valve hard, worked for me..

[ARWadsworth]

If it is not covered you are paying money for nothing. AFAIK it is covered under your heating care (the old 3* plan certainly covered it). I wonder if they add an inhibitor after they have drained the system, if indeed they do drain and not freeze.

-- Adam

[e-mail]

[Andy Hall]

I think it depends on which contract you have, but I believe so.

One year's contract premium is more than enough to cover the supply of enough TRVs for the entire house. BG don't pay retail, they just charge you above it :-)

Do let us know if they try to sell you power flushing when they fix this. I have a book running on it ;-)

.andy

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