If you want less heat output, replace that radiator with a smaller radiator.Also, i have a radiator in a first floor vestibule that is burning with heat and it appears to have a size "d" on it....if i put a smaller hole valve on there will it get less hot? its also pretty close to the boiler
its a vestibule it doesn't need that much heat wasted there
If you reduced the size of the vent enough to interfere with that rad heating - not that I'm sure that's entirely possible, but speaking theoretically - it'd also interfere with the heat traveling further, to the next rads on that line.
Peter - if you're reading this - might be amused to hear that last night, the vent by my desk was audible, for a minute or two.