Standards

What the markings actually record

Almost everything on this shelf carries a figure, and almost every figure gets read as a promise. None of them is. A nominal output records the point an appliance was tested at, not a range it will roam across; an efficiency percentage records a bench result on normalised fuel; an emission class records what left the flue under that same test; a required draft belongs to the chimney and is printed as though the stove supplied it. Each is exact, each is real, and not one of them says what will happen in your own house. Some are published documents; several of the things this trade calls standards are conventions with no publisher at all, and the difference shows up the day something will not fit. Each page says which it is, in four parts — what the document or the convention fixes, what it does not promise, what it works alongside, and which families on this site depend on it.