How to Diagnose and Replace a Hot Surface Ignitor | Step-by-Step Furnace Repair Guide

How to Diagnose and Replace a Hot Surface Ignitor

When your furnace suddenly stops heating, one of the most common causes is a failed hot surface ignitor. This small but essential component is responsible for lighting the gas to heat your home. In this guide, Adam from HVAC Bee shows you exactly how to diagnose, test, and replace your furnace ignitor safely and efficiently.

🎥 Watch the full video here:
👉 https://youtu.be/D87GPYCsq64

🔍 What Is a Hot Surface Ignitor?

A hot surface ignitor (HSI) is a small ceramic device that glows red-hot to ignite natural gas inside your furnace. When it fails, your system may blow cold air or refuse to start altogether. Over time, the ignitor can crack or burn out from repeated heating cycles — especially during the winter months when your furnace runs more often.

Common symptoms of a bad ignitor include:

• Furnace not igniting or producing heat

• Clicking sound without ignition

• Blower running but no flame

• Error code related to ignition failure

🧰 Tools You’ll Need

Before starting your repair, make sure you have the following tools ready:

• Multimeter (for testing continuity)

• ¼” nut driver or Phillips screwdriver

• Replacement hot surface ignitor (specific to your furnace model)

• Safety gloves and eye protection

⚙️ Step-by-Step: Diagnosing the Ignitor

1. Turn Off Power and Gas – Safety first! Always shut off the power to your furnace and close the gas valve before opening the access panel.

2. Locate the Ignitor – It’s typically mounted near the gas burners and connected with a small plug or two wires.

3. Inspect Visually – Look for cracks, white residue, or burn marks on the ignitor surface. These are signs of failure.

4. Test with a Multimeter – Disconnect the ignitor and check for continuity.

   • If there’s no continuity, the ignitor is bad and needs to be replaced.

   • If there is continuity, continue troubleshooting for other issues like gas flow or control board errors.

🔧 Replacing the Hot Surface Ignitor

1. Remove the Old Ignitor – Unscrew it carefully using your nut driver or screwdriver.

2. Handle the New Ignitor with Care – The element is fragile; avoid touching it directly with your fingers.

3. Install and Reconnect – Mount the new ignitor in the same position and reconnect the wires securely.

4. Restore Power and Gas – Turn everything back on and observe your furnace start-up cycle.

You should see the new ignitor glow red and ignite the gas flame — confirming a successful repair!

💡 Pro Tips from HVAC Bee

• Always verify your furnace model before purchasing a replacement ignitor.

• Keep a spare ignitor during heating season for quick repairs.

• Never use sandpaper or abrasive tools on the ignitor surface.

• If your new ignitor fails quickly, check your system voltage and ensure proper grounding.

🏡 When to Call a Professional

If you’ve replaced your ignitor but your furnace still won’t start, the issue may lie in the control board, gas valve, or safety sensors. That’s when it’s time to call your trusted local experts at HVAC Bee.

📞 Schedule your heating repair or maintenance today:
Visit https://hvacbee.com

We proudly serve homeowners throughout Cherokee County, Cobb County, and surrounding areas, providing expert HVAC service, repair, and installation.

🐝 About HVAC Bee

HVAC Bee is your locally owned and operated heating and air conditioning company dedicated to keeping Georgia homes comfortable all year long. From quick furnace fixes to full system replacements, our goal is to deliver buzz-worthy service with honest pricing and reliable craftsmanship.