We have a britony 8o, the hot water works fine, but when the heating is switched on it runs for less than a minute then it sounds like a plane, then cuts out, the pump/fan runs for a while then the boiler fires up again and goes through the same process. The boiler never stays on long enough to heat the radiators very much.The flow pipe gets hot but the return is almost cold. We used sentinel 800 a few weeks ago on the advice of the heating engineer who did the service but it only worked for a couple of weeks and we now have the plane back and lukewarm radiators.
Help!!!!!!!!!! Val