Hi Uselessdiyer, Your boiler will have a flow and return to the hot water cylinder - the connections usually go into the cylinder about 1/4 and 1/2 way up. There should also be a vent pipe in the top connection/pipe going up into the cold water tank. With the hot water being called for feel the flow and return pipes and they should be hot - if not it may be that the vent pipe is blocked - unblock it. If there is no vent pipe you will have to slacken the highest joint in the system to allow air out. Regards, stoneyboy
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!