Troubleshooting a Hot Surface Ignition System

Replacing Air Filter in a Furnace
Clogged filters are a common cause of furnace problems. It’s a good idea to change your filter once a month. JaniceRichard / Getty Images

Hot surface ignition systems are more efficient than standing pilots, but they still require occasional troubleshooting. Here’s how to troubleshoot your hot surface ignition system:

What Hot Surface Ignition Is

Hot surface igniters use electricity and conductive metal to light your pilot. When your furnace cycles on, a charge is sent to the heating element that lights the pilot. Hot surface ignition systems are more energy efficient than standing pilots and present less of a potential hazard in the event of a malfunction.

Identifying the Problem

A faulty igniter could be the result of several issues:

  • Igniter age. Electronic ignition systems aren’t designed to last for the lifetime of your furnace. Have a technician look at your furnace if you haven’t replaced your ignition system in several years. Installing a new igniter will require the help of a professional.
  • Mismatched igniter. Certain furnaces require specific ignition systems. The wrong igniter can cause malfunctions and ignition issues. Have a professional examine your furnace and install a new igniter if necessary.
  • High-temperature switch. Your high-temperature switch is a device that maintains safe levels of heat within your furnace. A clogged air filter can cause a backup of warm air and result in your temperature switch turning off the igniter prematurely. Temperature switches can also malfunction and prevent your igniter from lighting. Call a pro if your furnace doesn’t ignite after you’ve changed your filters.

Fixing your Igniter

Furnaces use gas and electricity to create heat. Working with gas and electronic systems can present a danger to yourself and your home. Always hire a professional to tackle furnace repairs.

Fortunately, not all troubleshooting requires the help of a pro. Here are a few simple fixes that don’t involve working with gas or electricity:

Change Your Filter

Clogged filters are a common cause of furnace problems. It’s a good idea to change your filter once a month. Here’s how to swap out your furnace filter:

  • Step 1: Buy a new filter. Filters vary based on efficiency and lifespan. Cheaper, disposable models come in multi-packs but provide less robust filtering. Washable filters are more expensive but offer excellent filtering abilities and last for several years.  
  • Step 2: Turn off the power. Look for a power shut off switch on your furnace or flip its breaker. Changing your filter won’t require working with electricity, but it’s always a good idea to work on power-free appliances.  
  • Step 3: Remove the old filter. Most filters are located on the side or at the bottom of the furnace. Be sure to note which side of the filter faces down. All filters have arrows marking which side should face down.
  • Step 4: Install your new filter. Place your new filter in the furnace making sure the correct side is facing down.
  • Step 5. Power up. Restore power to the unit.

Check Your Thermostat

Incorrect thermostat settings can cause furnace ignition issues. Be sure your thermostat’s setting is above the room’s current temperature. Also, be sure your unit is set to heat or auto. If your thermostat has a fan setting, make sure it’s set to on or auto. You can test your thermostat by raising the temperature to its highest setting. (Just be sure to lower it once the furnace kicks on.)

Check Your Furnace’s Power

Tripped breakers or accidently bumping the power switch can cut power to your furnace and stifle its ignition. Check your breaker box for tripped breakers. Overloaded breakers will have toggles in the off position. Ensure your furnace’s power switch is in the on position.

Check the Gas Supply

All furnaces have supply lines that feed gas into the unit. Most homes have two shut off areas. Exterior valves, also known as street side valves, are normally located near your gas meter on the outside of your home. Ensure the long side of the handle is parallel to the gas line. House-side valves are smaller ball valves. In older homes, these pipes are iron and coated in a black sheath.

Newer homes sometimes have a copper pipe that runs into the utility room. These pipes are known as high-pressure gas systems and have valves near your furnace or water heater. Most valves have clearly marked on and off positions. In the case of exterior valves, it’s a good idea to call a pro if you notice a shutoff. Many fire departments and gas companies prefer a trained technician to operate these valves.