Flushing the central heating system

[dilalio]

When I took the radiator outside and hosed it… clear water was coming out from the other side

I meant the pipework return to the boiler... Not the outlet of the rad.

 

[Nas1]

Yes ,the system pressure needs to be maintained,so a second person attending to that whilst you observe the water flowing from the valve would be ideal.

Perfect I shall do this. Also do I need to isolate the boiler from the system before I do this?

 

[dilalio]

If you have a filling loop on the return to the boiler, isolate boiler flow and open the filling loop. If rad in question is last before boiler, you'll only be reverse flushing the pipework between it and boiler. Best to shut all other rads off so that flow (reversed) has all pressure available to clear any blockages in that leg of pipe.

 

[spile]

I’ve a double ground floor radiator that is furthest away from the pump/boiler. It only warms up when I correctly balance the other radiators by closing (particularly the upper floor) lock shield valves the correct amount.

 

[dilalio]

I’ve a double ground floor radiator that is furthest away from the pump/boiler. It only warms up when I correctly balance the other radiators by closing (particularly the upper floor) lock shield valves the correct amount.

OP has declared he's balanced the system.