cold radiator at top of house

[helplessmum]

I hope someone can offer some general advice please.
My daughter has been in her first house for just short of a year. There is an attic conversion in the house and the radiator up there has never worked properly. Now the cold weather is with us we really need to sort the problem.
We have every intention of calling in a plumber but I am concerned about whether we are looking at a potentially major problem, or maybe just a minor one, and would like to be prepared!
The boiler (Vokera Option combi, sealed system) is in the cellar, the suspect radiator is in the attic. In case it is relevant, the vertical distance between the two is around 7 or 8 metres.

We tried bleeding the radiator but couldn't get it to fill with water. Logic said that there wasn't enough pressure in the system. Sure enough, the low pressure light was showing on the boiler. We topped up the system to the required pressure (I can't tell you what pressure this was as there is no gauge visible, we just kept going until the warning light went out)
We were then able to bleed all the air out of the radiator and it heated up.
Two weeks later, the low pressure light came on again, so we topped it up again. Every two weeks or so we have the same problem.
Yes, we checked for leaks - you would think that with losing that much water there would be a very large puddle somewhere - but couldn't find anything.
The only thing we can find is that the "overflow" from the boiler chucks out water for a couple of days after we have filled it up. But the radiator doesn't stop working until at least a week after that.
Any clues would be very welcome!

 

[ChrisR]

See "boiler pressure problems" and similar, in the faqs.

 

[Softus]

You have a faulty PRV. Replacing it will fix the problem. You need someone who knows what they're doing.

 

[helplessmum]

Thanks to your 2 guys for your answers. -
Chris R - I have looked for "boiler pressure problems" in the FAQ's and ended up even more confused - there seem to be about a million different things that could be the problem, mainly linked with leaks and possible heat exchanger problems. Still, I guess that's why I need to get a plumber in!
Softus - thanks for your suggestion. When you say I need someone who knows what they are doing, I assume a plumber will know, but do you suggest I get someone who specialises in the Vokera boilers or would any competent plumber be able to deal with it? would appreciate your further advice

 

[Softus]

What I meant was that you should find a heating engineer who's been recommended to you. Ask friends, family and colleagues who they use. He/she doesn't have to be CORGI registered if the only fault is the PRV, but it would be wise to find someone who is.

 

[fatoftheland]

Maybe not Corgi registered but need a certificate in Unvented

 

[mpbob]

The problem sounds like the radiator is to far away from the boiler.You say it is seven meters away,the pump in the boiler is only a 5 meter head so it will not pump up there,the water will take the shortest route.You will have to move the boiler higher up in the house,or try turning of all rads except that one,to see if it works then.If it does the rest will need balencing up,which means turning the return side down,till you get a even flow temp.Hope this will help

 

[Softus]

The problem sounds like the radiator is to far away from the boiler.You say it is seven meters away,the pump in the boiler is only a 5 meter head so it will not pump up there

1. You're talking nonsense.
2. You're responding to a post that's more than two years old.

 

[swbjackson]

Maybe not Corgi registered but need a certificate in Unvented

Why? It's a combi boiler not an unvented cylinder.