2 rads downstairs cold after flushing

[danmanchester]

Good guys,

Had a leaking drain valve on my open-vented CH system so I drained it, replaced the faulty drain valve but now 2 of the 3 rads downstairs are cold.

Assuming it was a balancing issue I turned off all other rads but no improvements. Then thinking it must be blocked I refilled the system and drained from the closest drain point to each rad 3/4 times - each time the water getting clearer.

After 3/4 flushes I thought it would be all good but now it's still not getting warm?! I've just added 1 litre of Fenox X400 'de-sludger' but was wondering if anyone else had any further ideas for me to try?

Thanks in advance

 

[petertheplumber12]

You may have an air lock in the pipe work, try turning off all the other rads and just have one of them open, then with the boiler off but the pump running, turn the boiler stat down, open and remove the bleed nipple and be ready to catch the water in a bucket you may get a bit wet, get someone to help since you want the water to come out in a steady stream for a while with only none valve open on that rad. when water comes out steady turn the valve off then open the other valve and repeat, if that works and with boiler turned up it heats up repeat for other rad. Then turn rest on and see how it is. If that doesn't work then you need a wet and dry vac and remove a valve from rad and suck from the valve to remove air.