Wood Fired Boilers Key Terms

Understand the basics of wood fired boilers

By Howard Robertson

As the name indicates, wood fired boilers use wood as a fuel to generate heat. Wood fired boilers have been used for many years and technology for these boilers has evolved to a great extent. However, you need to be aware of environmental restrictions while using boilers for residential, commercial and industrial applications.

Whether you want to use wood fired boilers for indoor or outdoor applications, you will need to be conversant with certain terms. This guide explains some boiler key terms, such as UL standards, NFPA 85, hydronic heaters program, hard water and AFUE (Annual Fuel Utilization Efficiency).

UL standards, Underwriters Laboratories

Several boiler manufacturers mention that their wood fired boilers are compliant with UL standards. This indicates that the products are in accordance with technical standards by Underwriters Laboratories and the safety of users is assured.
Try: You can read through the description of standards at Underwriters Laboratories, a reputable organization in the field of product safety certification and compliance solutions.

NFPA 85, National Fire Protection Association

NFPA 85 is another code that assures safe working of a wood fired boiler. There are various fire hazards associated with the operation of a wood fired boiler. NFPA (National Fire Protection Association) publishes NFPA 85 - the code for safe operation of boilers and combustion systems.
Try: You can read through the scope of updated NFPA 85 code at NFPA, a non-profit organization that publishes standards that are intended to minimize the possibility and effects of fire and other risks.

EPA's hydronic heaters program

US EPA (Environmental Protection Agency) has devised a program to encourage heating system manufacturers to improve air quality through developing and distributing cleaner, more efficient hydronic heaters. Hydronic heaters use a fuel such as wood to heat water that is then used to heat a building.
Try: EPA publishes detailed information on its hydronic heaters program.

Hard water

Whether you want to use a wood fired boiler for generating steam or for heating water, you will need to soften the water passing through the boiler. Hard water contains mineral salts that might deposit on internal surface of boiler components and reduce the efficiency of a wood fired boiler.
Try: Res-Kem Corp., a supplier of water treatment equipment, offers a glossary of water treatment terms, including hard water.

Heat exchanger

A heat exchanger is an important part of a boiler; it helps to transfer heat from one fluid to other. Depending on the flow arrangements, heat exchangers come in three types: counter-flow, parallel-flow and cross-flow.
Try: wiseGEEK, an information resource, provides useful information about heat exchanger devices and the different flow arrangements.

BTU (British Thermal Unit)

One BTU is the amount of heat needed to raise one pound of water 1°F from a starting point of 39.2°F.
Try: To understand the definition of BTU, you can refer to the glossary of water heating terms at GasNetworks.

GPM (Gallons Per Minute)

GPM is the unit of measurement of water flow through a boiler. While selecting a wood fired boiler, you must know your application requirements and indicate required water flow rate in GPM.
Try: Greenwood Technologies, a provider of renewable heating solutions, offers a glossary of wood heating terms, including GPM.

AFUE (Annual Fuel Utilization Efficiency)

AFUE indicates the heating efficiency of a boiler. Factors that affect AFUE are changes in weather, cyclic on/off operation of heating equipment and associated energy losses.
Try: For definition and explanation about AFUE, you can read through information available at Crown Boiler and Moose Heating & Air Conditioning.