Hi, i really need some help. first time i've used one of these sites so not to good. my boiler is working great with my hot water supply but the central heating comes on for a few mins and then goes off and then on again ect ect. The pipes are making a right noise as they get hot and then cold. i've read a little on the site and its pointing to the sensor. i can't find it and don't even know what it looks like. Am i on the right track or barking up the wrong tree? any help will be much appreciated.

