Boiler Terminology for Property Owners and Managers
With the return of heat season to New York City, we thought it might be helpful to provide a review of industrial boiler terminology for our clients with apartment buildings and commercial rentals. When you meet with experts like the service technicians at Calray Boilers, you will better understand any problems or repairs to your boiler system. This list is by no means comprehensive – there are literally hundreds of words used in boiler technology – but this is the most common nomenclature we use in our day-to-day work.
Industrial Boiler Terminology
Air preheater (APH)
This warms air that is used with fuel as part of the combustion process in the burner area of the boiler, removing moisture and making combustion faster and more efficient.
Aquastat
Aquastats are components that send signals to the burner to fire or stop firing, based on the temperature of water in the boiler tank.
Baffle
A baffle is a barrier that restricts the flow of fluid to create turbulence and increase the rate of heat transfer.
Blowdown
This is the process of removing impure water with too many total dissolved salts (TDS).
BTU
Short for British thermal units, a BTU is the amount of energy needed to raise a pound of water one degree Fahrenheit. Here’s a handy table with some conversions of heat and heat capacity involving BTUs.
| 1,000 BTU | = | 1 lb. of steam |
| 150 BTU | = | 1 sq. ft. of hot water |
| 34.5 lbs. steam/hour | = | 1 boiler horsepower |
| 1 boiler horsepower | = | 140 sq. ft. of steam radiation |
| 240 BTU | = | 1 sq. ft. of steam |
| 34,500 BTU | = | 1 boiler horsepower |
| 1 gallon #2 oil | = | 140,000 BTU |
| 1 cubic ft. LP gas | = | 2,550 BTU |
| 1 cubic ft. natural gas | = | 1,000 BTU |
| 1 kilowatt hour | = | 3,413 BTU |
| 1 therm. natural gas | = | 100,000 BTU |
Burner
This is where fuel, such as oil or gas, is combusted to heat water in the boiler tank.
Check valve
A check valve is a specific type of valve that allows fluid flow in only one direction – usually used to prevent backflow to parts like the boiler feeder.
Circulator pump
The circulator pump pushes water out of the boiler to distribution lines for kitchen taps, showers, laundry, and the like or to radiators.
Combustion
Combustion is an energy conversion process that involves the burning of a hydrocarbon (oil, gas, wood, etc.) in the presence of heat and excess oxygen. In a boiler, this occurs in the combustion chamber (aka firebox) where the burner is located.
Condensate
This is radiator steam that has cooled (condensed) and returned to its liquid form as warm water, to be returned to the boiler for reheating via the condensate return system.
Expansion tank
An expansion tank is a safety tank that can absorb excess pressure from the main boiler tank to prevent dangerous pressure buildups.
Exhaust stack
This is the chimney or flue that conducts combustion byproducts, like carbon monoxide, out of the boiler system and out of the building.
Feedwater
Feedwater is the fresh water that is supplied to the boiler, usually via an automatic water feeder with need detected by a sensor.
Feedwater line
This is a pipe that conducts feedwater into the boiler tank with the help of a boiler feeder pump that’s triggered automatically.
Flue gases
These are gases created after combustion, including carbon monoxide, carbon dioxide, sulfur dioxide, and water vapor.
Gaskets
Used to prevent leaks at joints, boiler gaskets are often made of steel. Other types of leak prevention in the system, including in pumps, are seals and O-rings.
Hartford loop
A Hartford loop is a safety piping arrangement still in use from the early 20th century to facilitate condensate re-entering the boiler more efficiently.
Heat capacity
This is the amount of heat that a fluid can store, typically expressed as kilocalories/kilogram/degree Celsius or joules/gram/Kelvin.
Heat exchanger
Heat exchangers are elements of the boiler system that transfer heat created by combustion to the water in the boiler tank. Heat exchangers are usually made of sturdy metal, like copper, cast iron, or steel.
Manometer
A manometer is a device that measures boiler pressure at various points in the system in relation to atmospheric pressure.
Pressure reducing valve
Required by law, this valve is a safety addition to release steam pressure that could otherwise become dangerous.
Return lines
Return lines, sometimes also called steam traps, bring condensed steam back from radiators in the form of warm water to be reheated and used again. This is much more efficient than heating fresh water from the boiler feeder and extends the life of the boiler as well as saves on fuel costs.
Supply lines
These are the lines that distribute water from the boiler to places where it’s needed, like hot water taps and radiators.
Total dissolved salts
Total dissolved salts, or TDS, is the amount of other chemical components in boiler water, important to analyze to prevent clogged pipes and valves, tank mineral scale buildup, and corrosion.
Working pressure
This is the pressure at which a boiler normally works, carefully adjusted for optimum performance within a safe range.
Call Calray Boilers for Your Seasonal Maintenance Check
New York City’s hyper-local, blue-chip experts
While we recommend regularly evaluating your boiler for problems and making sure all your safety equipment works properly, it’s no substitute for regular professional service. Having your boiler system checked over once or twice per year will lengthen its lifespan, save you money on fuel and water, and reduce the number of hassles you experience due to boiler malfunction.
Don’t wait until your boiler is running at peak levels this winter to find out you need parts repaired or replaced. We recommend an autumn service call to get it in tip-top condition and give you peace of mind heading into those wintertime subzero temperatures.
Call Calray Boilers today at 212-722-5506 or reach out online at your convenience to schedule an appointment via our website.