The chances are someone has done some work on the heating system since it was installed and to make their life easier, have popped a couple of valves on to stop water leaking while they work.
The trouble is, the bore of these valves is small and can often restrict the flow to the radiator stopping it from getting fully hot. There is also the increased risk of blockage if the system contains an amount of sludge, but If all is well, then leave them as they are.
DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!