Radiator thermostat when turned down it Turin’s them all off

Possibly you have the room thermostat in the same room as the radiator with a TRV on which is in conflict with the room thermostat! Which possible means that when you turn the radiator in question off it then sends a single to the boiler to turn of the heating. Only one of a possible answer

Either an existing one pipe heating system, or the system not radially connected properly OR teed flow and return on the same pipe. If you turn off one radiator this shouldn't shut down any of the others, they should all independently run on their own TRV or settings. Thanks Peter

In most systems radiators need to be balanced. That is, in normal operation they all receive a fare share of the flow of hot water from the boiler. If the radiator you describe is close to the boiler ( in terms of its pipe-work) then if you suddenly turn it on whilst others are all, already hot, it will take much of the heat but if still a problem in stead-state then you should look to balancing your rads, which involves adjusting the smaller valve on the other end of each rad ( assuming you have them)

Potentially the stat is mounted on the wrong side of the radiator this creates a noise,nowadays u can get a universal radiator stat that can be mounted on either the flow or return little bit more expensive but a better job,try shutting it off the rad and see what occurs to the heating system the whole point in having radstats is so that u can adjust the temp of the radiator independently,hope the helps along with the other answers.

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