not exactly sure what you mean - if you have a repair to carry out on the domestic water supply then yes it is possible to shut off the water and still have the heating running. water will not leave your heating system unless you drain it - unless you mean that you want to drain the heat exchanger in the boiler? if you are then DON'T try and run the boiler.
if running a combi system you can shut all the water off (hot and cold) centrally at the stop cock, one advantage of the combi. this should not affect your heating.
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!