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If your furnace clicks on but won't ignite, the problem is likely a failed hot surface ignitor (HSI). This small but essential component is responsible for lighting the gas that heats your home. Without it, your furnace can't produce heat, leaving you in the cold.
Contrary to common misconceptions, a high-quality MERV 8–13 air filter from a trusted source like Filterbuy doesn't cause strain; it protects parts like the ignitor bkeeping them clean.
This guide will cover everything from identifying failure symptoms to understanding replacement costs and deciding between DIY repair and calling a professional.
A furnace ignitor typically lasts 3–5 years and costs $30–$100 for the part, with professional installation running $150–$300 total.
Signs you need a replacement: furnace clicks but doesn't light, short cycling, or visible cracks in the ignitor element.
DIY-friendly steps:
Pro tip: Match the ignitor to your furnace model—universal ignitors work for many units, but OEM parts ensure the best fit and longevity.
Think of the hot surface ignitor as the match that starts the fire in your gas furnace. When your thermostat calls for heat, your furnace sends electricity to the HSI, which is typically made of silicon carbide or silicon nitride. It heats up to an extremely high temperature—often over 2,000°F—and begins to glow bright orange.
Once the ignitor is hot enough, the gas valve opens, releasing a controlled amount of natural gas or propane. As the gas flows over the glowing ignitor, it ignites, creating the flame that heats your home. Without a functioning ignitor, this entire process stops before it can even begin, leaving you in the cold. As the experts at Carls Cooling LLC note, this component is absolutely essential for the safe and reliable operation of modern furnaces.
A failing furnace ignitor often shows clear symptoms before it quits completely. Knowing these signs can help you diagnose the problem quickly and avoid a no-heat emergency.
One of the most obvious furnace ignitor symptoms is the absence of a glow. When your furnace tries to start, you should be able to see the HSI glow a bright orange-yellow through the furnace's viewing port. If you hear the furnace click on but see no glow, the ignitor is likely burned out or has an electrical issue.
Is your furnace trying to start, shutting down, and then trying again a few minutes later? This is called short cycling. It can happen when the ignitor is weak and fails to get hot enough to light the gas on the first try. The furnace's safety controls will shut the system down to prevent unburned gas from accumulating.
A physical inspection can reveal a lot. Turn off the power to your furnace and take a close look at the ignitor. It’s a delicate component, and even a hairline crack can prevent it from working. If you see any white marks, black spots, or visible cracks, it's time for a replacement.
Furnace ignitors are not designed to last forever. Constant exposure to extreme temperatures causes the material to degrade over time. If your ignitor is more than a few years old and your furnace won't ignite, it may have simply reached the end of its lifespan.
When you’re facing a furnace ignitor replacement, the cost is often a top concern. Thankfully, it's one of the more affordable HVAC repairs.
Prices can vary based on regional labor rates and whether the repair is performed during emergency after-hours service. While the part itself is inexpensive, the labor cost reflects the technician's expertise, travel time, and diagnostic work.
With the part being relatively cheap, many homeowners wonder if they can handle the replacement themselves. While a DIY hot surface ignitor replacement is possible for those with some experience, it's important to weigh the pros and cons.
If you decide to tackle this yourself, the process generally follows these steps, as outlined by HVAC Optimizer’s 2024 guidance:
Working with gas and electrical systems carries inherent risks, including:
Hiring a professional HVAC technician offers several advantages:
A standard hot surface ignitor has a typical lifespan of 3 to 5 years. Some newer models made from silicon nitride can last longer, but their longevity is still affected by several factors:
This is where your air filter choice makes a huge difference. Using high-quality Filterbuy pleated filters is a simple, low-cost way to extend your ignitor’s life by keeping the system clean and promoting healthy airflow.
You should replace your furnace ignitor as soon as you notice consistent issues. Don't wait for a complete failure.
Integrating this into your seasonal HVAC maintenance routine is a smart way to avoid unexpected breakdowns.
Our HVAC experts have seen it all. Here are their top tips for dealing with furnace ignitor issues:
Dealing with a broken furnace ignitor can be frustrating, but it's a common and manageable repair. Whether you choose to replace it yourself or hire a professional, understanding the symptoms and costs empowers you to make the right decision for your home.
The best way to prevent future breakdowns is through proactive care. Regular seasonal checks and, most importantly, clean air filters are your best tools. A fresh, high-quality pleated filter is the simplest and most effective way to protect your furnace components and avoid the stress of an early ignitor failure.
Ready to prevent your next mid-winter breakdown? Start with a new pleated filter. Keep your furnace protected—order fresh MERV 8–13 pleated filters from Filterbuy today.
A bad furnace ignitor may have a visible crack, a white or chalky spot, or a burnt-looking area. If it’s old, it might just look worn, but the damage isn't always visible to the naked eye.
If your furnace ignitor is not glowing, it's usually because it has burned out, has a crack, or there's an issue with the electrical supply to the ignitor.
You can expect to pay between $150 and $300 for a professional to replace your furnace ignitor. The part itself is usually $30–$60.
If you are comfortable working with electrical components and gas lines and follow all safety precautions, it can be a safe DIY project. However, for most homeowners, hiring a professional is the safer option.
A typical HSI lasts 3 to 5 years.
The most common causes of premature failure are restricted airflow from a dirty filter, power surges, frequent cycling, and physical damage from handling.
Yes. A dirty filter restricts airflow, causing the furnace to run longer to heat your home. This extra runtime puts more stress on the ignitor, causing it to burn out faster.
No. The hot surface ignitor lights the gas, while the flame sensor confirms that a flame is present. They are two separate components in the burner assembly.
No. The ignitor is essential for lighting the gas. Without it, your furnace cannot produce heat.
No. When you use the correct size for your system, high-quality pleated filters like those from Filterbuy provide superior debris protection without harming airflow. They are recommended by HVAC professionals for this reason.
