advice on radiators please

[vitasgerulaitis]

hello,
i removed a radiator from my sitting room a week or so ago, to do this i turned off the mains cold water and emptied the entire hot and cold water in my house ( i now realise that this was a mistake). i blanked off the connections to the removed radiator and filled up the system again, seemed hunky dory to me.
However, when i put on the central heating there are 3 radiators upstairs that dont get remotely warm, all the others in the house are scorching, these radiators worked fine before i started the whole process so i know they are not faulty or old.
Today i emptied the system again, (this time just the central heating) and filled and bled radiators from bottom to top, all hissing and filled well.........but, yes you guessed it, the 3 bloody radiators upstairs are still stone cold.
There is 1 radiator upstairs that works, but the other 3 remain cold.........if it helps they are the ones furthest away from boiler/tank.
HELP PLEASE!!!, winters coming and one of the dodgy radiators is in me childs room!.

Thanks, Vitas.

 

[ratonnastick]

are the three port valve or zone valves open when you fill up.

try closing the valves on the rads that work to force the air through.

you can try the nice risky way of attaching a hose to the drain drown and very slowly adding mains water (too much too quickly can flood your house)

 

[MANDATE]

I agree with 'rat'. It is an air lock in the pipework that is creating a resistance. Caused when refilling the system, water comes down the feed pipe to the 'flow' or 'return' pipe, at the 'tee' junction it goes both ways left and right and then starts to rise up the expansion pipe, but this blocks the escape route for some of the air. Air that accumalates in any radiators can be bled off but large pockets of air in the pipe need releasing or moving along into the radiators. I would try closing all radiators except one of the cold ones nearest the pump, then try bleeding that one till it is hot. If sucessful close that one and repeat for the next cold one.don't forget you may have to bleed the pump.
If this fails, I would suggest you close the valves on one cold radiator and remove it, then open each valve in turn and run off a bucketful of water and this will release the air and allow it to be replaced with fresh water.
I have even gone a stage further, by fitting clear plastic tube secured to 1/2 in tap connectors across from valve to valve. This way I could see what was happening, I could see the flow,the direction and the air bubbles and then when everything was ok I put the radiator back.
Just thought another tip to help shift a air lock is to increase the pump speed to the top setting.

 

[vitasgerulaitis]

i appriciate the advice lads but didnt understand a word of it!! i'm a very novice central heating DIYer.
i have tried turning off certain radiators and setting the -pump away, but the cold ones are still full of water so when i try to bleed them the water squirts out!!, .................can you explain in very basic terms the 'hose pipe' method, cos im sick of trying to bleed full radiators.
Much thanks,
Vitas.

 

[MANDATE]

The hose pipe method is basically connecting a hose pipe from the mains water supply (cold kitchen or outside tap) to the lowest drain off point.
Now when you open the drain and cold water tap you have the mains pressure applied to your central heating water. The effect is to push the existing water back up the feed pipe and/or the expansion pipe into the small feed tank, which by the way will already be full of water.
This action will also push the air along with the water and release it. The risk is that opening the valves too much means the small feed tank fills at too fast a rate and the overflow pipe can't deal with it and it overflows into your loft making one hell of a mess. That's the risk!
I would not attempt this method without the feed tank being empty and only if I could control the flow and observe the result at the same time.