What is "back boiler"

n. 1 a boiler that supplies a central heating and hot water system and is fitted into a fireplace recess, normally behind a gas fire 2 a similar boiler, that just supplies hot water, fitted behind an open fire or in a range.

A back boiler is a device which is fitted to a residential heating stove or open fireplace to enable it to provide both room heat and domestic hot water or central heating. The device is a water filled heat exchanger enclosed at the rear of the burning chamber with a hot water output at the top of the chamber and a cold water feed at the bottom.