My radiators individual work if the hot river is on, i've bleed them but didn't give support to the problem?
Answers: Without knowing what kind of heat system you have make it virtually impossible to give you an answer.
As already stated it could be a failure with the zone tap,3 port or two 2 ports?Has the system always be like that?some elder systems are designed to work this way or it could be wired wrong.
Bring surrounded by a corgi registered breakdown engineer,it should be a straight forward fix.
If your CH system is more than in the region of 5 years old, it's because the pump have failed. It requirements a new one.
If you've get a condensation boiler (the type that hangs on the wall and you've get no hot tank) the controls have gone wrong and you'll have need of to get a service cook up to reprogram it.
If your system has a electronic spigot in it it have properly seized.It may have a lever on the side of it.You may individual have to bring the top hat element changed depending on make.This stopcock should be some where practical the airing cupboard.Good luck.
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