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Hi. We have two radiators in our lounge which don't heat up like all the others in the house. We believe they are the last on the circuit. They have been bled (no air escaping) and both have a functioning tvr. We use a Magna clean and have had the system drained down and refilled. We have also installed a new central heating pump. The boiler is oil fired, a bit old but is serviced every year and has caused us no issues. Our thermostat is located in the hallway (it was there when we moved in). If we turn the thermostat up enough or turn the pump up to maximum the two radiators will get hot but we don't want to use excessive electricity/oil. We have measured the temperature in the hallway and the lounge and found the hallway is consistently warmer.


Would it be worth moving the thermostat to the lounge (it is on the opposite side of the house to the hallway) or are there any other ideas/solutions we could try. I am not knowledgeable enough to try balancing the rads but would get a professional in if that was the most likely solution.


Any help would be greatly appreciated.



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Balancing is fairly straight forward. 
you use the lock shield valve (opp end to TRV) by closing the lock shield down will reduce the rate of flow through the radiator thus takes longer to warm, opening the valve up will increase rate of flow and thus warm radiator quicker. So close down the hallway valve and open the lounge two. Usually you would have last one fully open and gradually close down the others as you work back towards the boiler. Thus you spread the heat throughout the building more evenly. 

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Balancing is almost certainly your problem..


But it can also be a bit of a dark art if you don't know the actual way the radiators are physically connected back to the boiler & pump..


To simplify the concept..


Imagine Four radiators equally spaced along a system..


If all valves were fully open the water would take the path of least resistance..    

and most of it would flow through the nearest radiator..

(The furthest away may never heat up).


So for example the four radiators, nearest to furthest, may need their valves opened to 25%  50%  75%  and  100%  to give equal flow..



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The way I've done it in the past where the plumbing layout is not obvious.:  All TRVs to be full open.

Switch the system on from cold. Walk quickly around to feel which one or two radiator inlet pipes start heating up quickest. The inlet is usually but not always the one with the TRV.

Switch off the system and close those tail valves then open them just a little; no more than 25%.

Repeat the process, the rate of heating up being a crude but adequate indicator of flow rate in any particular pipe.

Edited by Geoff1946
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Hi. My apologies for not getting back to you sooner. I have done as you suggested and it is much better. Thank you all for your help. Regards Patrick

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Glad it works better for you. You can keep tweeking it as needed. 

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