The Pilot Light Isn't Out (But the Furnace Still Won't Start)

Troubleshooting Electronic Ignition Systems

Modern residential heating systems in Sterling, VA, rely on electronic ignition to safely light the burners, replacing the old-school standing pilot light. This system is far more efficient, but when it fails, homeowners are often left confused. Since there is no physical pilot flame to check, troubleshooting requires a different approach. Let's walk through the key components and common reasons why your electronic ignition might be preventing your furnace from starting and contact Quality Air Experts with questions!

Furnace pilot light.

The Role of the Hot Surface Igniter

The hot surface igniter is a fragile but critical component, acting much like a glow plug. When your thermostat calls for heat, the system sends electricity to this component, causing it to heat up until it glows bright orange. Only then will the gas valve open and allow the gas to flow. When it comes to residential HVAC in Sterling, we often find that a burnt-out or cracked igniter is the simplest reason for a no-start issue.

Home furnace.

Understanding the Flame Sensor's Safety Role

Once the furnace lights, the flame sensor is responsible for detecting the flame's presence, ensuring that gas is not continually released without ignition. This critical safety measure is a frequent cause of trouble, especially if the sensor is dirty. Over time, soot and oxidation can build up, preventing the sensor from detecting the flame's signal. If this happens, we recommend gentle cleaning as a first step.

Furnace gas valve.

Checking for Gas Supply & Electrical Issues

A furnace that won't light may be starved of fuel or power, regardless of ignition type. To maintain regular Sterling residential heating, we advise checking that your furnace's gas valve is fully open and that the circuit breaker hasn't tripped. Since modern systems require a consistent electrical current to operate the blower, igniter, and control board, any interruption or low voltage will halt the heating sequence.

HVAC technician working on a furnace.

When to Call an Expert for Complex Diagnoses

While simple checks are helpful, issues like a malfunctioning control board or a faulty pressure switch require professional knowledge. The pressure switch is a safety feature that ensures proper airflow and ventilation before allowing ignition. If any part of the electronic sequence is interrupted, your furnace will shut down. Quality Air Experts and our entire Sterling residential HVAC team have the diagnostic tools and expertise to accurately service all systems.

"The Pilot Light Isn't Out" Infographic.

Keeping your home reliably warm is our top priority, especially during the cold season in Northern Virginia. If you've tried simple troubleshooting and your system still isn't working, we're here to help. Contact us today to schedule a diagnostic visit!

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