Boiler & Steam Systems

Steam Boilers Vs. Hot Water Boilers

• All heating boilers use hot water to produce heat, and most run on either oil or gas, though all-electric models are also available. Hot water boilers, sometimes called hydronic boilers, operate differently than steam boilers, however. Hot water boilers heat and then circulate hot water through pipes and radiators to heat a building, while steam boilers heat water to its boiling point, and circulate the resulting steam through pipes to provide heat.

Steam Boiler Characteristics and Identification

• If you have radiator that has valves that hiss and let air escape, chances are your heat is produced by a steam boiler system. You can identify a steam boiler by inspecting the boiler itself as well. Unlike hot water boilers, steam boilers do not have a circulation pump. Also, unlike hot water boilers, steam boilers have a sight glass mounted on the tank, allowing you to see the water level inside.

One- and Two-Pipe Distribution Systems

• Steam boilers can either be part of a one-pipe or a two-pipe system, depending mostly on the age of the boiler. One-pipe distribution systems are more common on boilers from the 1920s and older and, as their name suggests, use a single pipe to circulate steam heat throughout a home. Two-pipe distribution systems are almost always found on steam boilers installed since the 1920s. They use both supply piping and return piping; steam rises through the supply piping and returns to the boiler through the return piping. Two-pipe systems are more efficient as well as easier and more economical to replace.

Problems and Considerations

• Steam boilers are a bit more susceptible to leaking then hot water boilers, but otherwise they quite reliable, and many of them can be expected to function for 50 years or more with proper care and maintenance. Steam boilers should be cleaned and inspected regularly, and should also be periodically tested by a professional service technician to keep them running at peak efficiency.