Please can someone help, I have an old coal fire with back boiler which heats my water and then clicks over to heat my radiators. I have a swtich in the kitchen that comes on when the water is heated and the radiators are being heated. For the past month the water is being heated however the boiler doesnt seem to be flicking over to heat the radiators, the house is freezing! I have tied bleeding the radiators but this doesnt seem to be the problem. I dont even know where the back boiler is as I believe it may be behind a wall somewhere? Any advise would be most appreciated as my toes are really cold now!!!