A boiler is a furnace that heats water. A forced hot water boiler is a type of boiler in which water is heated by a gas or oil-fired burner and circulated through pipes to radiators, radiant floors, or baseboard heaters. Forced hot water boilers use mechanical pumps to circulate the water. This allows the boiler to reach high temperatures quickly and evenly distribute the heat throughout the home. As a result, forced hot water boilers are an efficient and effective way to heat a home.