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Furnace Talk: How Is Electronic Ignition Different From a Standing Pilot Light?

If you’re trying to troubleshoot your gas furnace or are about to buy a replacement, you’re probably wondering what people mean by “pilot light,” “hot surface igniter,” and other technical terms. Don’t worry: below, we’re going to decode some jargon about furnace ignition (or, the way a furnace lights up).

By the time you’re done reading this, you’ll know what all of these things are and how they work:

  • Standing pilot ignition
  • Intermittent pilot ignition
  • Hot surface ignition

How Standing Pilot Ignition Works

As its name implies, a standing pilot light is supposed to remain lit at all times. It’s a small flame with its own gas supply and a sensor called the thermocouple. As long as the thermocouple can sense the pilot light’s heat, the flame will continue to get gas. If the thermocouple can’t sense the pilot light, it will shut off the gas to your furnace as a safety precaution to prevent a dangerous gas buildup.

The pilot light is situated at the front of the furnace’s burners. When the furnace needs to start a heating cycle, this little flame ignites the gas supplied to the burners.

How Electronic Ignition Works

There are two types of electronic ignition systems used in newer gas furnaces: intermittent pilot ignition and hot surface ignition. If your furnace was manufactured within the last 20 years, it most likely has one of these two ignition methods.

  • Intermittent Pilot Ignition. While a standing pilot light is always lit, an intermittent pilot light only comes on when your furnace is about to start a heating cycle. An electronic igniter creates a high-voltage spark to light the pilot flame.
  • Hot Surface Ignition. Furnaces with this type of ignition contain a part called a hot surface igniter, which is basically a ceramic fork positioned by the burners. When the furnace is ready to start a heating cycle, this ceramic component gets so extremely hot that it ignites the gas supplied to the burners.

Which Ignition Type Is Best: Standing Pilot or Electronic?

Of the three, standing pilot ignition is prone to wasting the most energy, and it’s also the most susceptible to problems due to the pilot light blowing out or something obstructing the pilot light burner. These are the main reasons why this ignition system has been phased out of newer furnaces.

Intermittent pilot and hot surface ignition require less energy than standing pilot ignition because they only burn fuel precisely when you need to use your furnace. They also tend to require less attention than a standing pilot light. Keep in mind, hot surface igniters can burn out over time, but replacing this part is relatively easy.

Get in touch with HVAC & Plumbing Unlimited today at (703) 454-5040 for quality heater installation or replacement in Northern Virginia you can count on.

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