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Radiator at top of house not heating up properly

All heating system seems to be working OK except for one radiator on the 2nd floor (boiler is in the basement).

The radiator doesn't heat up fully despite both valves being fully open and there also seems to be a temperature difference across the radiator with the bottom being hotter than the top. I've opened the bleed valve but I can open it several turns and leave it for over a minute without any water coming out.

Any help?

The pressure on the boiler is at about 1.5 bar

6 Answers from MyBuilder Plumbers

Best Answer

your rad has air in it ,if you have a combi system you need to fill your system up every time you let water out as it is a sealed system and needs to be topped up via your inlet taps but only fill to 1.5 bar , this is a job best done with 2 people as you will be up and down ,so one tops up and the other bleeds the rad. if its a conventional system make sure your header tank is letting water into your system,again a 2 man job makes it easy.


Answered 19th Dec 2011


Try turning all rads off apart from the one in question. It maybe a case of correct balancing of your heating system. My point is that the other rads are getting more heated water than the top one so close all other rads to send heated water directly up to the problem rad first.

If not then you will have to investigate problem radiator/valves and go from there either new rad trvs or new rad.


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Answered 19th Dec 2011

Sounds like a possible air lock. What plumbing system do you have combi or gravity fed system? It is sensible to fit an auto air vent on the top radiator as this is where air will normally end up (top of the system). If you turn all other radiators off by one one valve this will focus all the heating pumps effort on to your one radiator. This extra pressure should move the air lock out. You said you can bleed for over a minute (is air being released or nothing at all?). If this sounds like it is getting too technical and beyond you then it would be best to consult an expert by posting your job on this site. Sometimes you can move an air lock to another part of the system (although usually it will come out of the air vent or into the expansion vessel in the boiler). Auto air vents cost £10-15 and replace the key vents.



Answered 19th Dec 2011

Hi, it sounds like one of the valves is stuck or the bleed valve is clogged.

My guess would be jammed valve, this is a job for a plumber as the system will need to be drained.


Answered 19th Dec 2011

sounds like one of you valves is not opening correctly or there's not enough pressure in you system i advise you contact a heating engineer


Answered 19th Dec 2011

I suspect you have tanks and cylinder system ie not a combi boiler , and the feed and exspansion tank is not high enough to give pressure to that radiator, either lift the tank higher or make the system pressurised by fitting an exspansion vessel. however if you have a combi ther will be a slight blockage in the bleed valve outlet , just stick a pin in it but be careful it might shoot hot water at you. After your 2nd posting i now know you have a combi, there is air in the radiator because you said the bottom of the radiator gets hot,so take the bleed valve out and stick a pin in the hole,it may be advisible to turn of the radiator at both sides while you do it.


Answered 9th Jan 2012

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