by ericmark »
Wed Jan 23, 2019 2:19 pm
Most likely it's not radiator that is not working at fault, but the ones which are working.
In the main radiators have two controls, a TRV and a lock shield valve, the latter should be set so there is about 12 degs different between in and out pipes.
However I normally shut the valve let radiator get cold, then open bit at a time until it starts to warm up again, normally around 2.5 turns.
Basic idea is to cause a resistance in each radiator so all get a share of the hot water.