Living in Canada, having a furnace is a must. But they’re big, complicated and if not maintained well, they can also be costly. So how can you be a knowledgeable consumer and feel comfortable knowing your way around your furnace? Furnace Repair Markham has put together this description of how a furnace works and the top 7 commons furnace parts that are prone to break to help save you time and money!

Top 7 Common Furnace Parts that Are Prone to Break - ventilation system, thermostst, parts, heat exchanger, gas valce, furnace, ducts, burners, blower

A standard HVAC system is a furnace with a thermostat – the most common type is a gas-powered central air system. The thermostat reads the temperature of the air around it and when the temperature is below the number the thermostat is set to, it sends a signal to the furnace to turn on. Once the signal is sent, fuel is sent to the burners (in a gas-powered furnace) and the burners are ignited. The sensors in the furnace confirm all the burners are lit and heat a device called the heat exchanger. Air is pushed through the heat exchanger so it can evenly warm the air. Once the air reaches the desired temperature a blower motor pushes the warm air through the home’s air duct system.

More elaborate furnaces can have a humidifier to regulate the humidity; air conditioning to cool the air; and an air filtration system to improve the air quality in your home.

That was easy, right?! Just remember these 7 main parts of your furnace:

  1. Thermostat
  2. Gas valve
  3. Burners
  4. Heat exchanger
  5. Blower
  6. Ducts
  7. Ventilation system

It probably comes as no surprise that these are also the 7 common furnace parts that are prone to breaking. Furnace repair in Richmond Hill provides some helpful tips as to why these furnace parts may not be working and how to troubleshoot them.


First make sure that the thermostat’s display is on and lit. If it’s not, the batteries may be dead or there might be a blown fuse in your electrical panel. If this is not the case, turn the thermostat breaker off and safely remove the cover. Check for debris build-up and safely clean the area with a soft brush or a compressed air cleaner. If the thermostat is on and the display seems to be working, check that the date and time are correct, as it may be set to a program.

Gas valve and Burners

When the thermostat sends the signal to the furnace to turn on, the gas valve opens and ignites the burners in the combustion chamber. But if your furnace isn’t turning on, check to see if the pilot light is on – there should be a blue light. If the burners are yellow, you can clean them with a vacuum cleaner by turning the power and gas off first. If the pilot light isn’t on, there may be debris or there may be an issue with your thermocouple, which is a safety device that ensures your gas valve isn’t sending gas into the furnace.

Heat exchanger

If the heat exchanger isn’t working, there won’t be heat coming through the ducts. There are a few reasons why your heat exchanger isn’t working, but the most common are debris build-up and insufficient water flow.

If there’s debris build-up, run a CIP cycle to clear out any excess debris. If this doesn’t work, it may need manual cleaning. Insufficient water flow can also cause the unit to lose productivity – check the pressure and flow rate.

Blower & Ducts

The likely reason for a furnace blower to stop working is the blower fan. First check your thermostat and make sure it’s set to your desired temperature – a thermostat set to a lower temperature won’t be blowing warm air. Also check to make sure the thermostat is set to the right mode – if it’s on cool air mode, it won’t be blowing warm air either! However, if the thermostat is adequately set and still not blowing air, check the furnace circuit breakers. Lastly, check to see if the entire unit itself is on. If it is, then the likely problem is the fan.

If the issue is with the fan, either the fan itself needs to be repaired or there is a build-up of debris and dirt. The furnace should have an inspection window – look inside for any debris build-up. Also ensure there is a green flashing light. If the light is flashing red, there is a problem and a service technician will need to be called.

Ventilation system

A dirty air filter can prohibit air flow through the house. If the air filter is full, replace it and this may help to get the blower moving again. If the air filter was clean or replacing it didn’t help, check the outside of the ducts to ensure the seams are intact and air isn’t leaking. Additionally, go to each vent and check for any debris or furniture that could be causing a blocked vent.

Increasing the lifespan of your furnace

Now that you know some ways to troubleshoot your furnace, it’s also important to know how to increase the lifespan of your furnace, which could save you some money over time.

Top 7 Common Furnace Parts that Are Prone to Break - ventilation system, thermostst, parts, heat exchanger, gas valce, furnace, ducts, burners, blower

Here are 3 easy ways to get the most life out of your furnace:

  1. Regular service visits – we can help you with that! A Smile HVAC technician will look for signs of wear and damage before major issues arise.
  2. Change the filter – the easiest way to stay on top of this is to mark the date the filter should be changed in your calendar.
  3. Keep your furnace working efficiently – this means keeping windows and doors closed and keeping the furnace on a consistent schedule. You may even want to reduce the hot or cool air flow on days when you will be away from the home for long periods.