Components of a Home Steam Boiler

Boilers can be used to either supply hot water (hydronic systems) or steam for heating the home and can be fueled by electricity, oil, gas, wood or coal. Steam boilers were popularly used in the early 20th century. For simplicity, the components listed in this article are exclusively for steam boilers.

Boiler

The boiler in a steam heating system is an enclosed metal container where water is heated to make steam for the home heating system. The three most common types of steam boilers are cast iron, water tube and fire tube. Water tube and fire tube boilers are usually found in commercial and industrial applications, while cast iron is more suitable for low-pressure home use. The combustion efficiency of cast-iron boilers ranges from 75 to 93 percent, depending on the type and design of the heating system.

Heat Source

Steam boilers can use electricity, oil, gas, coal or wood. gas ring 1 image by PeteG from Fotolia.com

Electricity is the simplest heat source for the home owner, though it might not be the most efficient or the cheapest. Oil and gas are common heat sources, and both are used in some systems with dual fuel burners. Coal and wood have a few advantages over the other fuels but present several additional problems, such as fuel storage and delivery and ash removal.

Automatic Water Feeder Valves and Cutoff Switch

The automatic water feeder valve is used to maintain the water level in the boiler at the proper level. The low-water cutoff switch cuts off the heat source if the water level falls below a safe level. Even though the water in a steam boiler system is recovered after the heat is removed from the steam, some water is inevitably lost, making the water feeder valve necessary.

Vents/Flues and Vent/Flue Dampers

A gas-tight flue for conducting the products of combustion outside the home is required for all fuel-burning systems. gas flue image by Alison Bowden from Fotolia.com

A gas-tight chimney or flue for conducting the products of combustion outside the home has to be provided for all fuel-burning systems. Unfortunately, heat is also lost through the vent. Mechanical vent dampers are mechanical devices that close the flue as soon as the boiler stops firing. This minimizes heat-loss through the flue, saving energy and money. Gravity vent dampers rely on gravity to close the flue and can cause back drafts.

Piping, Valves and Radiators

Heat Is delivered to the room by radiators. abstraction in the office image by jeancliclac from Fotolia.com

The steam is carried through the home through an arrangement of piping and valves that varies among different systems. One or more pressure-relief valves will be installed somewhere on this system of pipes and radiators, and will automatically open and release steam if the pressure becomes too high. The heat is finally delivered to the room air by way of radiators, an arrangement of tubes that allows for the efficient exchange of heat from the steam to the air.

References

• Inspectapedia: Dictionary of Heating Boiler Components
• HP HVAC: High Performance Boiler Information
• Home Heating Systems and Solutions: Home Heating Boilers

Resources

• WorldCat: Home Heating and Air Conditioning Stystems