When a furnace stops providing heat, the issue may stem from a malfunctioning furnace lighter. The lighter, an essential component in most modern gas furnaces, ignites the fuel needed to heat the air. Without it, the furnace cannot function properly, leaving the home unheated and uncomfortable. Understanding how to diagnose a furnace lighter issue is crucial for both safety and efficient operation.
The furnace lighter, often referred to as an igniter, comes in two common types: the hot surface igniter (HSI) and the intermittent pilot igniter. Hot surface igniters use materials such as silicon carbide or silicon nitride to glow red-hot and ignite the gas, while intermittent pilot igniters create an electrical spark to light a small pilot flame. Both types serve the same purpose but differ in design and operation.
Signs of a failing furnace lighter include the furnace failing to produce heat, even when powered on. Often, the blower will activate, but the burner remains unlit. A clicking sound may accompany this failure, particularly in systems using spark igniters. Another concerning symptom is the smell of gas, which can indicate a significant safety hazard. If gas is detected, the furnace should be turned off immediately, and a professional should be contacted.
Diagnosing a furnace lighter issue begins with turning off the furnace. Power to the furnace should be switched off at both the thermostat and the breaker box to ensure safety. After allowing the furnace to cool, the next step involves locating the igniter. The igniter is typically situated near the burners and can be accessed by removing the furnace panel. A visual inspection may reveal cracks, chips, or discoloration on the igniter, which are clear signs of damage. Additionally, the wiring connected to the igniter should be checked for loose or damaged connections.
Testing the igniter’s continuity with a multimeter provides further insight into its condition. By setting the multimeter to measure resistance (ohms), the igniter’s terminals can be tested for electrical flow. A healthy igniter generally shows resistance within a specific range, often between 40 and 200 ohms, depending on the manufacturer’s specifications. If the multimeter shows no reading, the igniter is defective and must be replaced.
If continuity testing reveals no issues, the next step is to test for proper voltage delivery to the igniter. After reconnecting the igniter wires and restoring power to the furnace, a multimeter can be used to measure voltage. If the igniter is not receiving voltage, the problem likely lies with the control board or associated wiring.
Several common issues may explain a furnace lighter issue. A broken igniter is the most straightforward to address, as replacing it with a compatible part typically resolves the issue. In cases where the igniter is simply dirty or blocked, cleaning it gently with a soft brush or cloth can restore its functionality. However, the igniter should not be touched directly with bare hands, as oils from the skin can damage its surface.
Other issues, such as a faulty control board, may require professional intervention. If the control board fails to send voltage to the igniter, it must be inspected and possibly replaced by an HVAC technician. Similarly, problems with the gas supply, such as closed valves or blockages, can prevent ignition even if the lighter is functioning correctly. Diagnosing and repairing gas supply issues should always be handled by a qualified professional due to the inherent risks.
Although homeowners can often identify and resolve basic furnace lighter problems, certain situations necessitate professional assistance. Persistent gas odors, repeated igniter failures, or complex control board issues are best addressed by trained technicians. Annual maintenance is also crucial for preventing lighter issues. Regular inspections, keeping the igniter clean, and replacing air filters help ensure the furnace operates efficiently throughout the heating season.
When a furnace lighter issue arises, quick and accurate diagnosis can make a significant difference. Addressing the issue promptly ensures not only a warm home but also the safety of its occupants. For comprehensive furnace maintenance and repairs, contact Patriot Heating and Cooling. Our experienced team provides reliable service to keep your home comfortable all winter long.