Beware that even if only one "expert" says the central cooling installation (my concept of these absurd things) must be in place, then if nothing else your insurer might invalidate your policy if it is blocked - even if you want to claim for something else (easy way out of a claim, yes, I don't think much of insurance companies), never mind if it was something directly related to the gas installation. This is one of the unfortunate aspects of having anything gas fired in your house. That said, if the boiler is independent of air from the cooling system then you would be OK to block them. If you ever want to rent out your house then you must have a landlord's certificate for the gas installation - that would soon tell you. These things cost £30-45 to obtain from a registered gas installer.