A foot away is more than enough IMO, and as already mentioned, there are no set distances in this case. Almost any distance from the side of the radiator is unlikely to cause problems, as the majority of the heat will be rising due to the convection principle that radiators work on, rather than being dispersed out the sides.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local