cold rads upstairs

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Hi can anyone help save my sanity?? I recently drained down my central heating system as i had a leaking valve and while it was drained down decided to replace a downstairs rad to a double. When i refilled the system i added an inhibitor to the new rad, bled all the rads and switched on. All downstairs worked a treat but 3 upstairs rads stayed cold. These are original rads so probably about 30years old. I tried bleeding them and the next day one went hot but two still refuse to play. I have tried to bleed them (taking out about 8 litres of water out of each one so there is no air in them)I have felt the flow and return pipes on the combi boiler and both get red hot so water is obviously going round the system. Any help greatly appreciated.
 
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Either air lock, or the draining shifted a load of crap that is now blocking the flow.
 
turn off the hot ones, and see if the others warm up.

If so, balance the system.
 
Either air lock, or the draining shifted a load of crap that is now blocking the flow.
Thanks ben. would i be better off taking these rads off and refitting them to see if it improves any? a steady stream of water comes out of both bleed valves although one is yellowish in colour(maybe the inhibitor?not sure) and one is pretty clear.
 
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turn off the hot ones, and see if the others warm up.

If so, balance the system.
Read something last night on the forums about 'balancing' the system. This is where you turn all the rads off upstairs to try and get hot water through right? Tried this last night and the pipe upto the valve did get quite warm but rad stayed cold.
 
did you turn off ALL the others?

did the pipes at both ends of the rad warm up?

has it got a TRV?
 
did you turn off ALL the others?

did the pipes at both ends of the rad warm up?

has it got a TRV?
Hi John. I just trned off the ones upstairs. It has got a trv and it warmed up on one end only. (not the side with the trv)
 
turn off ALL the others.

Take the thermostatic head off the TRV and check that the pin springs fully out.
 
turn off ALL the others.

Take the thermostatic head off the TRV and check that the pin springs fully out.
Many thanks john. Did as you said rads warmed up straight away without taking the trv head off. My two daughters especially send their thanks as they no longer have to put up with near arctic conditions ;)
 
OK, now you just need to balance the system. Turn off all the lockshields and then open each of them about a quarter of a turn to start with. What you are looking for is a temperature that makes the Flow pipe of each radiator, under the valve "too hot to hold" and the Return pipe at the other end "too hot to hold for long". It needs very little movement on the lockshield to make them too wide open, so proceed slowly. It is easier if you start with the rads all cold. Check them again after half an hour or so.

If you find any room warms up much slower, or faster, than the others, make a tiny adjustment to its lockshield valve so that all rooms are about the same. The room with the Room Thermostat in should warm up a bit slower than all the others, so you know that when the stat clicks the heating off, all the other rooms are also upo to temp. You should have a rad in this room without a TRV or it may prevent the room stat from controlling the boiler and saving energy.
 

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