4 Parts Of Your Gas Furnace That Must Be Inspected Annually

Your gas furnace has provided the heat that's kept your home warm for the past several years. However, after years of heavy winter usage, your furnace's various components have sustained wear. If these worn components continue to be used excessively, then they can become hazardous. Hire your local HVAC technician to inspect these four components of your gas furnace before every winter season:


Your furnace's thermocouple creates the electricity that's required to open the valve that delivers gas to your burner assembly. Thermocouples are made of two types of metal (typically iron and copper) that turn the heat from your pilot flame into electricity. The electricity generated by your pilot flame's heat travels through your thermocouple and opens your gas supply valve when you activate your furnace.

However, since your thermocouple is made of metal, it's susceptible to developing metal fatigue. Whenever metal components experience significant fluctuations in temperature, they expand and contract. Eventually, the fatigued sections of your thermocouple will break and fail to produce the electricity that's required to open your gas valve.

Pilot Flame Assembly

The pilot flame inside your furnace is tasked with creating the flame that's required to ignite the gas that passes through your supply valve. When your furnace activates, it will begin the ignition process by sending a small amount of gas through your pilot flame's gas tube. The gas sent through your tube is then ignited by a small spark generated by your igniter.

Once your pilot flame is lit, it produces the heat that allows your thermocouple to regulate the flow of gas through your furnace. However, if your pilot's gas tube is dirty, or if your igniter isn't able to create a spark, then your pilot flame can't be lit. As a result, your furnace simply won't be able to activate.

Heat Exchanger

Anytime gas is ignited, it will release carbon monoxide. Your furnace ventilates the carbon monoxide produced by your burner assembly through a series of tubes known as a heat exchanger. Your heat exchanger ventilates carbon monoxide through a flue and out of your home.

Similarly to your thermocouple, your heat exchanger will develop metal fatigue. However, since your exchanger is in closer proximity to the heat produced by your burners than your thermocouple, it experiences far greater temperature fluctuations than your thermocouple. For this reason, manufacturers design their exchangers to be extremely durable.

After several years of use, your heat exchanger can develop small cracks that will leak carbon monoxide. Typically, cracks caused by metal fatigue will form in the weakest points of your exchanger—such as weld points and bends.

Carbon monoxide that leaks out of your exchanger will be blown into your home. If you continue to use your furnace while the exchanger is cracked, then you're likely to experience symptoms of carbon monoxide poisoning. Exposure to carbon monoxide at a volume of 70 parts per million or greater will result in chest pains, nausea, vomiting, and (in severe cases) even death.

Burner Tubes

Soot will collect inside your furnace as gas is ignited. The majority of the soot produced by your furnace will settle inside your burner tubes. If your burner tubes become filled with large soot deposits, then the airflow to your burner assembly will become restricted.

As a result of restricted airflow, your burner assembly will operate less efficiently and create even more soot. As soot production increases, your burner assembly is likely to ignite the soot that settles on your burner assembly. A smell similar to burning asphalt will ventilate throughout your home whenever soot is ignited by your burners.

Each of these four components can create serious problems for you and your household members. For this reason, hire your HVAC technician to inspect these components of your furnace before you plan to use your furnace on a daily basis. Otherwise, the safety and comfort of your household will be at risk.