What to Know Before Furnace Repair

Updated: October 2023

If you have a furnace, chances are one day you will find yourself in need of furnace repair. When that day comes, it will be a good idea to know a few basics about the furnace you are using at home. This way, you will be able to communicate more easily with any technician who will be helping you in your furnace repair.

First thing’s first: you need to know what type of furnace you have. Modern furnaces are usually referred to by their efficiency of heat use, and whether they use propane (less common) or natural gas (more common). You may also have an oil heating system. Most older furnaces have an efficiency of 50-60%, while newer furnaces can range anywhere from 80-100% efficiency. When speaking of efficiency, we are saying how much of the generated heat will go into the actual heating of the house, and how much will be vented away to the outside without having been used. When looking at furnace repair, you may hear some discussion about the efficiency of your furnace.

It’s also helpful to have a basic knowledge of the parts and setup of your furnace. As you will most likely not be doing the actual furnace repair (a certified technician should absolutely be called), a simple familiarity with some of the major terms will be sufficient:

• Gas line – Where the gas enters the furnace from an outside source.
• Shut off valve – Stops the supply of gas to the furnace.
• Pilot light – Small burning flame which stays lit and serves to light the burners.
• Electronic igniter – Electric alternative to a pilot light. Does not stay lit, lights the burners much as a spark plug.
• Burner – Where the gas is ignited in order to provide heat for the household.
• Heat exchanger – Area inside the furnace which the burners heat up. Air moves through the heat exchanger in order to become warm.
• Blower and circulating fan – Takes cooler air out of the house, moves it through the heat exchanger (where it becomes warm), and pushes back into the house.
• Ducts – The ventilation through which the air travels around the house and back to the furnace.
• Filter – Screen designed to take dust and small particles out of the air circulation, helping both to improve air quality and to keep the furnace clean.
• Flue pipe – Removes to the outside of the house carbon monoxide and any other exhaust produced from burning gas. Older furnaces often vent through the chimney; newer, more efficient furnaces do not produce as much exhaust and, therefore, may vent through a small, independent pipe.