AFUE (Annual Fuel Utilization Efficiency): A measure of a boiler’s heating efficiency. The higher the AFUE percentage, the more efficient the boiler.
Aquatube: Water-tube boilers where water circulates through tubes which are surrounded by combustion gasses.
Blowdown: The act of removing accumulated particles and sediment from the bottom of the boiler.
Boiler: An equipment designed to heat water or produce steam.
Boiler Blowdown: The process of removing sediment or dissolved solids from the bottom of the boiler or the boiler drum.
Boiler Log: A record of boiler operating conditions.
Burner: A device that introduces and ignites fuel in the combustion chamber.
Cast Iron Boiler: A boiler made of cast iron sections.
Circulator Pump: A pump used to circulate water in hydronic heating systems.
Combustion Chamber: The part of the boiler where fuel is burned.
Condensate: The water produced when steam cools and condenses.
Condensing Boiler: A boiler that recovers heat from the flue gasses.
Corrosion Inhibitor: A chemical added to boiler water to prevent corrosion.
Deaerator: Equipment that removes dissolved gasses from boiler feedwater.
Draft: The difference in pressure causing combustion gasses to flow through the boiler.
Dryback Boiler: A firetube boiler design with an open rear in the combustion chamber.
Electrode Boiler: A boiler where electrical current passes through the water to heat it.
Expansion Tank: A tank used in hydronic systems for the expansion and contraction of heating fluid.
Feedwater: The water supplied to the boiler for conversion into steam.
Firetube Boiler: A type of boiler where combustion gasses pass through tubes surrounded by water.
Flame Safeguard: A system ensuring safe burner operation.
Flue: The duct for the escape of combustion gasses.
Foaming: The formation of foam or bubbles in the boiler.
Heat Exchanger: A device that transfers heat between two fluids.
High-Pressure Steam Boiler: A boiler that operates at pressures above 15 psi.
Hot Water Boiler: A boiler that produces hot water for heating.
Hydronic Boiler: A boiler using water as the heat-transfer medium.
Low Water Cutoff: A safety device that turns off the burner if water level drops below a safe level.
Low-Pressure Steam Boiler: A boiler that operates at pressures up to 15 psi.
Make-Up Water: Water added to a boiler system to offset water lost.
Modulating Boiler: A boiler that adjusts its firing rate as per the current demand.
Packaged Boiler: A boiler that comes as a complete package.
Pilot Light: A small flame that ignites the main burner.
Pressure Gauge: An instrument measuring the pressure of steam or water in the boiler.
Pressuretrol: A control used to maintain pressure in steam boilers.
Radiator: A device made of metal used for heating.
Return Line: Piping that brings condensed water back to the boiler.
Safety Valve: A valve releasing pressure from the boiler if it exceeds safe levels.
Scale: Hard deposits formed on boiler surfaces due to water impurities.
Stack Damper: A device in the flue controlling draft and reducing heat loss.
Stack Temperature: The temperature of the flue gas as it exits the boiler.
Steam Trap: A device removing condensate and non-condensable gasses from the steam system.
Steam Trap Survey: An inspection of all steam traps in a facility to determine their condition.
Thermocouple: A device detecting the presence of the pilot light.
Turndown Ratio: The ratio between maximum and minimum fuel input rates of a modulating boiler.
Vertical Tubeless Boiler: A type of firetube boiler with combustion gasses passing vertically through the tubes.
Wetback Boiler: A firetube boiler design where the combustion chamber is surrounded by water on all sides.
Zone Valve: A valve controlling the flow of water or steam to different zones in a system.