one cold radiator

12 Jan 2009
Reaction score
United Kingdom
Hi, I am new to this site, Please help!

I have a combi boiler and 7 radiators, one of the upstairs radiator was not heating up at all and the other was only getting luke warm so had the system power flushed out and also had 4 new rads replaced at the same time. Since then the luke warm rad is warming up more than before but the cold rad is not warming up at all.
The pipe leading to the TRV is warm and if I turn the other upstairs rads off then the cold rad warms up but then if I turn the others back on than the cold rad goes cold again. The other rads upstairs are also warm at the top but cold at the bottom.
The 3 rads down stairs which are closes to the boiler are red hot.

Any suggestions on what to do next?

Many thanks.
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With 7 rads the first thing that comes to mind is poor pipe work design.
Just sounds like you need to properly balance the system. Water flow is lazy like a lot of boiler installers it will take the shortest and easiest route if it can. Try reducing the flow to the hottest rads by the lockshield valves to give better flow to the coldest radiator.
the people that flushed your boiler and replaced your rads should have balanced your system; get them back to do it.
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thanks, it turns out that the pipe work maybe fitted on a one way pipe system instaed of two, I have somebody coming to have a look tomorrow, will keep you posted, thanks.

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