I own a condo and the heating is from a hot water radiator. We have a hot water radiator at the living room and there is quite a noise (some clanking but mostly like water running on a pipe) coming from it even though the main valve is all the way off. The one in the bath and bedroom make no noise on or off. Any tips appreciated.
It depends partly on your location but many radiator systems have bypass pipes through which water passes to and from other radiators on the same circuit - even it that particular radiator has it's valve turned off.
Air in the heating pipework can cause the sort of noises you describe and can be eliminated by bleeding the air from the system
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