Top 7 Common Furnace Parts That Are Prone to Break

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There is nothing worse than a furnace breaking during the winter. We have all been in that situation, and dread the thought of it happening again. Fortunately, Smile HVAC can provide a quick turnaround for furnace repairs. Knowing how a furnace works, and what parts commonly break, can help you identify an issue more accurately.

We provide affordable and effective repairs for HVAC systems in the GTA. Smile HVAC can fix your furnace quickly, because no one should have to go without heating, especially during the winter.

What is a Furnace?

A furnace is a type of heating unit that is used for the central heating of a house. You may be familiar with a boiler, that heats up water, in order for it to pass through radiators and emit heat. A furnace works in a similar way, except it heats up air, which is then distributed by vents.

A furnace’s differing application of heat means it has many unique components compared to a boiler. These components need to be fully understood, in order to correctly diagnose issues with a furnace.

How Does a Furnace Work?

When the furnace is switched on, it will power the thermostat, which will indicate to the furnace when heating is required. The inducer motor is the first component to start, which begins cycling the air through the heat exchanger. The heat exchanger is where the air heats up, before it is sent out to each room in the house.

When the inducer motor has begun pushing air through the heat exchanger, the gas control valve will be opened and the igniter will turn on. The gas will run through the valve and ignite when it is emitted through the burners. At this point, a flame sensor will ensure there is a flame present, otherwise it will turn off the gas, as a safety precaution.

The burners will now be heating the air that is flowing through the heat exchanger. After a couple of minutes, the blower motor will turn on. This pushes the air out of the heat exchanger and into the rest of the house.

How to Diagnose a Problem With Your Furnace

When there is a problem with the furnace, there is usually a blinking light that indicates what the issue is. The blinking itself corresponds to a code that is either in your furnace manual, on the control board, or on the inside of the furnace door. While the blinking light may not be able to tell you how to resolve the issue, it should indicate what component is experiencing problems.


Here are the seven components that are liable to break and how you can decrease the likelihood of them becoming damaged. Before you start investigating the cause of your furnace issues, you must ensure the power switch is off.

Inducer Motor

As mentioned before, the inducer motor causes the air to move through the heat exchanger, and allows for a constant flow of oxygen into the system. This is one of the components that is most likely to break as it can over heat if the evaporator or furnace filter is plugged.

Blower Motor

A blower motor is another component that is prone to breaking and this is because it relies heavily on a clean filter. If the furnace filter is not cleaned regularly, then the blower motor has a difficult time recirculating the air. This will cause the blower motor to seize up and overheat, meaning it will not be able to regulate the airflow properly. Make sure you change your furnace filter every 1-3 months to prevent blower motor failure.

Control Board

The control board is where electronic signals are sent to different parts of the furnace depending on what the thermostat indicates. When the control board becomes faulty, you may find that the furnace becomes unresponsive to the thermostat’s signals, by either not turning off at the correct temperature, or turning on at the wrong time. This can often happen due physical damage, which is identifiable by scorch marks on the circuit board.

Gas Valve

The gas valve is also prone to becoming broken, often due to age. Newer furnaces usually have an electronic gas valve, which means a component in the gas valve itself can sometimes become faulty and not allow the gas valve to open. To prevent your gas valve from breaking prematurely, have a furnace tune-up before the winter, to ensure it is in optimal condition before its constant use.

Heat Exchanger

The heat exchanger is under constant pressure, which is why it is also liable to becoming broken. This is also the component that, if identified as the source of your heating issue, should never be turned back on. This is because a leaky heat exchanger could disperse carbon monoxide into your house which is extremely dangerous.

Ignitor

A faulty ignitor will not ignite the gas when it comes out of the burners. Consequentially,  the flame sensor will shut the system down as no flame will be detected. Ignitors can become faulty due to age, or even an electrical surge, if the power exerted has fried the internal components.

Evaporator Coil

Finally, the evaporator coil can become plugged, particularly if you have not replaced your furnace filter for a long time. This can cause the unit to run less efficiently, and for heat to build up in the rest of the furnace. Ensuring the evaporator coil is unclogged will help increase the longevity of your furnace.

We understand how frustrating it can be when a furnace breaks, and that it is not always easy to tell what component has become faulty. We can help you replace broken components in your furnace quickly, and ensure it is up and running as soon as possible.