What to do if one radiator is cold?

[BloooCowWonders]

All the others are fine.

Several years ago we had some plumbing work done and were told to close off all the rads, and open then starting from the one farthest from the boiler. It worked then but hasn't this time (different house)

Dies anyone have any other ideas?

bleed them?

Have you bled it with a radiator key? (sorry, probably the first thing you did!)

Only to do it again

Are you sure you got them in the right order?

bleed the cold one. Is it cold all over?

Yes, get a bleeding key and release the trapped air. Do it while it's on, so you can feel it warming up. Don't scald yourself though.

If bleeding doesn't work it might be like ours which often needs measures like this uk.answers.yahoo.com/question/index?qid=20091003061731AAi9Amk

BOF that made me chuckle, I came over all cockney.

Bleeding hell get a bleeding key and bleed the bleeding radiators, can you adam and eve this op eh?

Heh heh

turn off all the hot ones.

If the cold one stays cold, it has a blockage; or has been turned off at one end; or has a seized TRV.

If the cold one warms up, you need to balance the radiators (all of them)

as Piglet says and balance them by shutting down/up the locksheild valves on the rads ,it takes a bit of time but is worth the effort.

TRVs are bad news especially in hard water areas or due to the fact that they are never moved, the control pins seize in place and the themostatic value of the valve ceases to function. I never use them due to being unreliable and a general pain in the ass.

Me too, with TRVs. Some OK others not. Did what was advised and turned them all up to full during the summer months. The next winter, one wouldn't work properly, even when taking it off. Messed around with the pin to loosen it, and eventually worked again. Turned it down low, and then stuck again and couldn't get it to open more.

I have this problem. One radiator. I have tried all the bleeding bleeding I can think of. What do you mean by TRV?

We had this, we had to have the pipes and radiators flushed, not sure of the technical terms, sorry. They forced water through the whole system and cleared out the dirty stuff, all radiators worked perfectly after though. Apparantly it needs do every once in a while.

there are now some very effective system filters that trap circulating particles before they can settle into sediment and cause a blockage. They started getting popular in the last ten years, and in the last two or three years some better ones came out by other established manufacturers. Typically about £100 plus fitting, which can be done by a DIYer with basic plumbing skills and tools. Many boiler installers strongly recommend, or insist on, fitting one because it reduces future problems.

As long as this is done before the sediment gets bad enough to cause a blockage, a chemical treatment to loosen existing sediment will usually get it clean enough to save the cost of a powerflush.

Once it has got bad enough to cause a blockage it is much more work and expense.

TRV is Thermostatic Radiator Valve. Quality varies, Danfoss, Pegler and Drayton are very good. Unbranded cheap ones are also available.

They are liable to stick, especially if they are left screwed down during the summer; if they are set at typical room temperature they will tend to move up and down with warm and cool weather. Dirty water from corrosion particles probably makes them worse. It is often possible to free off a stuck pin but it is very tiresome.

The thermostatic head, often plastic, can go wrong and can be removed and replaced, especially if it is a major brand and readily available.

We have one radiator that doesn't warm up too. I never turn mine down in the summer. Not sure what the problem is though. Will follow the tips on here and see if I can sort it.

One of ours went cold, we bled it to no avail, then dh found something on YouTube about fixing such a problem, I can't remember the technical details but it was something to do with moving a 'needle' inside the radiator which apparently was quite easy to do, following the guide on YouTube:

link here

Ah, OK, I didn't realise that TRV meant the individual thermostat on each radiator. Familiar with the thingy, but not the correct name for it! Thanks, Piglet.

Useful link, thanks, happynappies.

It was probably the pin in a TRV stuck. You can let a single drip of WD40 run down the pin off a pencil tip, then try to get the pin moving up and down (it has a spring to push it up). I find a soupspoon in the palm of the hand good to press it down, the curvature of the spoon helps the pin to stay upright rather then bending to the side or even breaking, and spoon spreads the pressure over your hand instead of the pin punching through the skin.

Some people suggest using a hammer on the pin, this is much more likely to bend or break it.

You remove the thermostatic head from the TRV to gain access to the pin. No water will come out. Turn it to highest setting before taking it off or putting it back.