Troubleshooting an Intermittent Pilot Ignition System

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Close up of gas burning furnace jets. Michael Interisano / Getty Images

Intermittent pilot lights ignite only during heating cycles. This design is more energy efficient than other pilot light designs, and reduces the chances of a gas leak. But intermittent pilots aren’t without problems. Here’s a quick look at commonly encountered issues with intermittent designs and some tips for solving them:

Intermittent Pilot Lights

Intermittent pilots use electronic ignition systems to create heat.

When an electric signal is sent to the burner, a solenoid releases gas into the pilot and warms a heating element or emits a spark to ignite the gas. The burner is then activated and warms the home. The burner and pilot shut off when the correct temperature is reached. Intermittent designs boost the efficiency of your home and present less danger in the case of a malfunction.

Identifying the Problem

  • No ignition spark. The ignition spark is what lights the pilot and begins the warming cycle. A lack of power to your ignition can stem from a variety of issues:
  • No furnace power. Check your breaker box for tripped breakers. Some furnaces also have on-unit power switches. Many of these switches look like normal light switches. Check to make sure yours is in the on position.
  • Incorrect thermostat settings. The wrong thermostat setting is a common source of faulty ignitions. Check to make sure your thermostat is in the on and heat positions. The temperature setting of your thermostat can also play a part. Be sure the setting is higher than the current temperature of your home.
  • Loose connections. Your intermittent ignition system is electronic. Loose internal furnace connections can interrupt signals. Call a pro if you suspect this is the problem. Working with electrical systems is dangerous and may cause damage to yourself and your home if handled incorrectly.
  • Damaged electrode. Spark electrodes can wear out due to age or damage. Spotting a damaged electrode is difficult and will require the help of a professional.
  • Faulty control module. Your control module is a circuit board that controls the signals and input from other electronic devices like your thermostat. These boards can fail due to age, electrical surges and damage. Have a pro swap out your control module.
  • A visible spark but no pilot light. Your pilot light is what ignites your burner and creates heat. Gas-related issues are typically the cause of pilot light failure.
  • Loose pilot valve wiring. Your pilot valve is a small device that opens and closes to release the small burst of gas that lights your pilot and burner. Most of these switches are electronically controlled. Loose or corroded wiring can cause your valve to remain closed.
  • Damaged pilot gas line. The gas that ignites your burner arrives to your pilot through a gas line. These lines can become pinched or damaged over time. These restrictions can limit the amount of gas released into your pilot, resulting in a lack of ignition.
  • Clogged pilot line. Burning gas can sometimes release moisture. An overabundance of water can corrode or clog your pilot line.
  • Plugged or damaged pilot burner. Similar to the pilot line, the pilot valve light itself can become clogged. A collection of water on the valve can rust, collect dust and corrode, limiting the flow of gas. Older burners can also deteriorate due to age. Constant burning can weaken the metal housing and cause it to crumble and block gas.
  • Burner doesn’t stay lit. Your burner is what provides heat to your home. Ignition issues with your burner vary and are usually related to a larger electronic or gas problem. Here’s a quick look at potential issues:
  • Electronic sensor problems. A lack of current flowing to your flame sensor will result in a momentary ignition. This can result from the lack of a proper ground or circuit polarity issues. Either of these problems will cause the gas valve to fail.
  • Bad wiring. The wiring in your burner can deteriorate over time. A faulty ground or live wire will cause inconsistent signaling to other electronic devices in your burner.

Always call a professional if you’re experiencing issues with your burner. Tackling a faulty burner will require working with potentially dangerous electrical and gas systems.

Fixing the Problem

Addressing ignition and burner problems will require working with electricity and gas. Unless you have experience working with these systems, it’s best to hire a pro. Attempting a DIY repair can result in serious damage to your home and furnace — and may also threaten the safety of your family.