One radiator is cold


2 Dec 2010
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United Kingdom
I have installed a combi Boiler about 2 months ago. We have 3 radiators upstairs and 3 radiators downstairs. The system was fully flushed when new Boiler was fitted.

One of my radiators downstairs has always been cold (Pipes are cold too). I have replaced all the TRV valve on all the radiators. If I close all the TRV valves all the other radiators apart from the downstairs cold radiator work (very Hot). As soon as I begin to open the other TRV valves on other radiator, the downstairs radiator start getting cold again.

Any Idea Please
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You explanation wasn't completely clear to me so let me confirm. One radiator is cold when the others are working? That same radiator is hot if all the others are switched off?

If so you need to balance. That radiator is at the end of the chain, or at least the part of the pipe network with the least pressure. There is no water left for it when the other radiators are allowed to take it. Balancing is the process of partially closing off some or all of the other radiators to leave enough pressure to send water through the last radiator. Your heating system will work much better for it.
Thanks for your reply

Spot on!

how do I balance my Central Heating System?

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