Top 7 Furnace Parts that Usually Break

A furnace is a heating unit that is commonly used for the central heating of a house. Put simply, a furnace heats the air, which is then distributed by vents around the home. A furnace has several unique parts, which you should take the time to diagnose any issues that might arise with your furnace correctly.

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In the cold winter months, your furnace is possibly one of the most important appliances you rely on every day in your home. You need it to keep you and your family warm and comfortable. If something goes wrong, you instantly know about it, and in the coldest weather, you’ll want to identify the cause as quickly as possible! If it has stopped working or if there are some unusual noises or you just feel something isn’t entirely as it should be, have a look at our guide to the most common parts that are prone to break to help you identify the cause of the problem and help you fix your furnace today..

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The Thermostat

The thermostat is like the central heating system; it instructs the furnace what temperature to run at and how long it is to keep running to warm up your home and keep it that way. According to Smile HVAC Service and Installation When it malfunctions, it doesn’t mean the entire heating system is broken. Still, it does, unfortunately, mean that it’s no longer receiving the correct information to heat your home as desired, so it will need attention so you can heat your home again.

The Gas Valve and Burners

When firing up, your thermostat will signal the furnace, which tells it to turn on ready to heat your home. Next, the gas valve opens and lights the burners in the combustion chamber. If your furnace isn’t firing up, first check to see if the pilot light is turning on – If it is, you’ll see a blue light. If the pilot light isn’t on, there may be an issue with the thermocouple, a safety device to stop your gas valve from sending gas into the furnace. There’s also a chance of debris on the pilot light that needs removing. If you plan on checking this yourself before calling in a professional, please turn off your power and gas first!

Heat Exchanger

If it’s your heat exchanger that’s broken, air won’t be able to flow through the ducts. Check your heat exchanger (the series of coils and tubes where the air is heated) for cracks and debris. If you suspect a cracked or broken heat exchanger, it’s essential to get it looked at quickly by a professional as it can emit dangerous gases that you do not want in your home. If this happens, please turn off your furnace. It’s not worth risking the potential damage it could cause.

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You can check your blower is running correctly by looking into the furnaces inspection window. There should usually be a flashing light, green or red. And as you might have guessed, green means your blower is running okay, and if it’s red, you should call for service, please double check this in your manual, though, in case your particular furnace doesn’t operate in quite the same way. If there are no lights, the problem may be with the thermostat, the run capacitor or the furnace control board (to name a couple of options), and you should get someone to check it out for you. The blower’s performance is also heavily affected by the filter. If your filter isn’t regularly cleaned, then your blower will have trouble recirculating the air.

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The ducts work alongside the blower in your furnace and perform the critical task of distributing the heat around your home. If you have noticed an almost annoying and unusually loud noise, it might be due to a leaky duct – you also might find that your home doesn’t seem to be heating up evenly, with particular rooms heating better than others. Again, this signifies that hot air is escaping somewhere in the ductwork, and they either need cleaning or replacing.


If you’ve noticed a reduced efficiency from your furnace recently, it could be that your filter needs to be replaced. You need to ensure your furnace has regular tune-ups to keep running at its best. This will ensure your air filter works effectively by reducing the amount of dirt and dust your system has the filter every day. Replace and maintain your filter to benefit from cleaner air, lower utility bills and increase the life of your furnace. 

Control Board

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The control board is where electronic signals are sent to different parts of the furnace, depending on the thermostat shows. 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 it on at the wrong time. This can often happen because of physical damage, which is identifiable by scorch marks on the circuit board.

The furnace, as you may have guessed, is a complex piece of equipment with many parts that could go wrong; it recommended that you take the following steps to improve the longevity of your furnace and reduce the risk of a significant fault occurring:

● Get your furnace checked every fall to identify any issues and make sure everything is in tip-top condition as you enter the period where it will see heavy usage.

● Replace your filter – Every time it gets dirty, a dirty air filter can kill your furnace.

● Increase efficiency. Your furnace is working hard; find ways to take the strain off of your system. Seal up any air leaks, especially from your basement or attic.

Even the most well looked after, regularly serviced furnace will sometimes develop a fault. It’s recommended if this should happen, you consult a professional to help identify a fault or repair broken parts.

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