6 Heating System Terms You Should Know

Whether you're facing a heating installation or repair project, it's a good idea to know how to talk about the situation with a professional. Here are 6 terms that will benefit you immensely while you have that conversation.

British Thermal Unit (BTU)

A BTU is a measure of how much energy is required to heat a single pound of water by one degree Fahrenheit in an environment that's about 30 degrees. You will often see the capacity of systems listed in BTUs on a yellow sticker that's attached to the box and to the machine itself.

One major advantage of the BTU is that it allows you to make comparisons between systems running different types of fuel. If you're looking at units that operate on natural gas, heating oil, and electricity, for example, this will let you make as close to an apples-to-apples comparison as possible.

Annual Fuel Utilization Efficiency (AFUE)

Measured as a percentage, AFUE is a measure of how economical a system is. An AFUE of 85% on a system, for example, means that 85% of the fuel spent in the process of making heat is converted to usable energy while the remaining 15% is waste or loss. Note that AFUE only refers to the heating unit itself, and it largely applies to liquid and gas fuels. You will usually find the AFUE figure on the same sticker that has the BTU rating.

Multi-Stage Heating

This style of heating unit is designed to only use its peak capacity on the coldest days. You may be able to save a lot of money on utility bills by installing such a system.


Most systems have filtration units installed. The required filters are usually serviceable by hand. A clogged filter can cause many problems, ranging from poor airflow to burner to odd smells.


This refers to the total interior space that has to be heated. This includes the rooms themselves, walls, insulation materials, and roof. It is essentially the entire structure at large.


Most of the better modern systems on the market today allow for control of different zones in the house. This means you can set your bedroom to a warmer temperature than the entertainment room, for example.

Zones are also very useful in doing diagnostics for heating repair work. Setting each zone to the same level can help you identify problems with the distribution of heat, potentially pointing to blower motor issues.

For more information, contact a heating contractor today.