boiler — A boiler is a device which burns gas, oil, electricity, or coal in order to provide hot water, especially for the central heating in a building.
broiler — A broiler is a part of a stove which produces strong heat and cooks food placed underneath it.
double boiler — a utensil consisting of two pots, one of which fits partway into the other: water is boiled in the lower pot to cook or warm food or melt a substance in the upper.
steam boiler — a receptacle in which water is boiled to generate steam.