Various issues can prevent your furnace from igniting. Some can be resolved without calling for help, but most require a licensed professional for diagnosis and heating repair. We’ll explain a few potential reasons for your furnace not igniting and how they can be fixed. Ignitor repairs are relatively easy for a trained technician. Do not attempt to replace the ignitor or perform any other furnace repair yourself.

Failed Ignitor or Pilot Light

The ignitor is the heart of a modern furnace’s electronic ignition system. If the ignitor is dirty, burned, or has failed, a technician must replace it. One way to determine if the ignitor is faulty is to listen for a clicking noise when your furnace starts up; it can indicate the ignitor has failed. You can also check the part for damage (it’s usually located near the center of the burners).

The pilot light can be relit if it goes out. However, if it won’t stay on after a couple of tries, the pilot system may be defective. Continuing to run your furnace can become a fire or carbon monoxide hazard. Power down the system and call for help. If the pilot system is damaged, it will have to be replaced.

Faulty Flame Sensor

The flame sensor is a metal rod attached to a wire that detects when a burner flame is working. If it does not sense the flame, it shuts down the furnace. Otherwise, the unit can overheat, components can burn out, and gas can build up to dangerous levels. 

A malfunctioning sensor can prevent the burners from igniting in the first place (if it can’t read the flame, it may shut off the furnace for no reason). The flame sensor is easy to replace. However, we recommend having an HVAC technician do it for you.

Gas Line Problem

A blocked gas line is one of the most common reasons for a furnace not igniting. An obstructed gas valve can also prevent enough natural gas from reaching the ignition system. Since the furnace won’t provide any warmth, call a technician as soon as possible. They can check for and clear any debris or objects clogging the gas line. 

Another problem may be the line is too small. In this case, the technician can install a larger pipe, an adapter to connect to a larger gas line or an adjustable regulator. They’ll also make sure the new gas line isn’t oversized, which can damage the pressure regulator, safety controls, and other internal components.

Dirty Burners

Dirt, rust, or grime on the burners can cut off the oxygen supply they need to light. Cleaning the burners requires removing them from the system and, after any debris is removed, re-installing them. A professional has the tools and expertise to do this quickly and safely.

Malfunctioning Thermostat

If the thermostat isn’t signaling the furnace to produce heat, the system will not ignite. Call a professional if the thermostat is damaged or not working correctly. You’ll need a heating repair professional if the unit has faulty connections, sensors, or wiring.

Frequently Asked Questions

If My Furnace Is Not Igniting, Are There Any DIY Fixes?

Before you call a heating repair company, you can try the following:

  • Check the Thermostat: The thermostat should be set to “Heat” mode and at a temperature that requires the furnace to ignite and provide heat. If not, reset it accordingly and see if the furnace turns on. If the thermostat doesn’t turn on, replace the batteries. Or, if the unit is in the path of sunlight, a draft, or near a heating appliance, move it to a different location.
  • Replace the Filter: A dirty or blocked filter can restrict airflow and prevent the furnace’s burners from igniting. The filter should be replaced every 1 to 3 months, depending on usage and indoor air quality. But if your furnace isn’t working properly, check the filter regardless of when you last changed it. Installing a new one can resolve the issue without calling a contractor.
  • Find the Circuit Breaker: Your furnace should be on a dedicated circuit. If the circuit breaker trips, it will cut power to the heating system. In the electrical panel, look for the tripped breaker in the middle position and flip it to the “Off” position. Wait a few seconds and move it to the “On” position; the furnace should now turn on and ignite again.
  • Close the Furnace Door: If your furnace’s access door is open, the safety switch will prevent it from igniting. Close the door if necessary, make sure it’s secure, and see if your furnace turns on.

Can a Furnace Repair Technician Fix Any Ignition System?

At Express Plumbing Heating & Air, our technicians are trained to fix any furnace ignition system. A standing pilot light may fail or the problem can be with a gas valve control or thermocouple (a heat-sensing tool in pilot-controlled furnaces). An intermittent pilot ignitor is an electronic ignition system that turns the pilot flame on only when heat is required. Other furnaces use a hot surface ignitor with a fork-shaped heating element; a temperature increase from this part triggers the gas valve to open.

Should I Replace My Furnace?

An ignitor problem is a common reason for furnace repair. Replacing your furnace may make sense if it’s over 10 years old, has had frequent repairs, and other issues are present. Our trained experts can help you decide whether to repair or replace the unit.

How Do I Know If the Issue Is Gas-Related?

Check that the gas supply is turned on and the valve is open. Testing another gas appliance can also help determine if there’s a gas supply issue. If you suspect a gas leak, evacuate your home and call 911.

Furnace Not Igniting? Call Express Plumbing Heating & Air

If your furnace won’t ignite, you can contact us in an emergency and we can reach your home in less than 30 minutes. We know how important it is to have heat in Idaho’s climate. Our fully trained, licensed technicians can repair your furnace and make sure it’s ready to handle peak demand. Prompt and reliable, they can resolve any problem so your furnace is safe, efficient, and functional. For a thorough diagnosis and accurate quote, call (208) 203-8948 today.

Brad Jordan

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