This question bothers me for a long time but i can't find any good words on the web. In my house (in the country) we have to burn coal to warm water (both, for regular use and to keep the house warm). I wanted to know how to name the device that you shovel coal into and set it alight. Afaik furnace is used in ironworks in order to melt metals whereas stove is could be synonyms to a fireplace or alternatively to mean "a cooker" / be used to heat a pot. Afaik a boiler is that big cylinder used to store hot water (could have a gas or electric heating system attached to it directly), but what i want to describe is specifically the big stove with 3 doors that is used to heat water that later travels thorough pipes to boiler and radiators.

How do you specifically call this big green object next too the boiler and how to say that you want to start it (ignite it)?