Show home heating hints by john barclay heating expert W HILE a poker frequently is a handy implement to use on a furnace let me caution you against using it for the purpose of agitating the fire bed from above that results in a lot of trouble for you and for your furnace stirring the fire through the furnace door opening only mixes ashes with the live coals creating clinkers As you know clinkers choke a fire and prevent the coal from burning freely and completely ely also they clog the grates making it difficult to shake the fire properly owing to the odd size and shape of lumps of coal at the point that is poked from above the fuel bed becomes packed and this packing prevents the free passage of air thus forming clinkers clinkers formed this way however cause less trouble for ordinarily they can be broken up a and nd dropped into the by gently shaking the grates |