Furnace Ignition Failure: 6 Top Causes

Is your furnace giving you problems? Professional Services' expert HVAC technicians can help!

The last thing you want to deal with on a freezing cold day is a furnace that won't turn on. All heating systems may experience problems, resulting in no heat. Furnace ignition failure is the main culprit, but what causes a simple ignition function to fail in the first place?

As top-rated "furnace installers near me" serving Southeastern Wisconsin, the team from Professional Services provides superior furnace repair and replacement services. Below are six causes of a failed heating system and what to do about them.

#1 Thermostat Settings

If your property’s heating system isn't firing up, check the thermostat first. Have you adjusted the settings from "off" to "heat?" 

Check the thermostat, adjust the settings if necessary, and give the furnace a few seconds to click on. If it doesn’t work, there’s another problem. Thermostats that have malfunctioned will either need you to replace the batteries or call an HVAC technician for repairs.

#2 Gas Line Problems

Issues with the gas line, like a clog, can also lead to an instant furnace ignition failure. That problem is simple since any obstruction in the gas valve or gas supply will prevent enough natural gas from reaching the ignition. That means the system won’t trigger the combustion process or generate heat.

The only thing to do in this situation is to call a professional furnace technician to evaluate your unit and ensure that it has a sufficient gas supply coming through to it. These teams can also find out whether there are city gas line blockages, such as invading tree roots or debris, that might be causing your natural gas supply problem. Plus, if the technician's inspection determines that your current gas line is too small for your heating system, adding extra piping or an adjustable regulator can solve the problem.

#3 Tripped Circuit Breaker

A power surge that trips your home's circuit breaker could be why your furnace is experiencing ignition failure. Many gas furnaces use a pilot light to ignite burners and combust fuel. However, electric furnaces and modern gas furnaces use an electric ignition system instead.

Still, whether you have a modern gas furnace or an electric one, you'll have ignition problems if the furnace lacks electricity. If your electrical system has a power surge while the furnace is consuming electricity, the excess power can also overload the circuit and trip the breaker. You can remedy this problem by flipping the circuit breaker back into the "on" position so that the furnace has enough electricity to fire up. 

#4 Dirty Air Filter

You might not think that a dirty filter could cause an issue, but it’s often the culprit for furnace ignition failure. Experts recommend changing your HVAC air filters at least once a season. A filter swap every 30 days is best if the unit works hard or your area is dusty or polluted.

The air filter traps airborne particles as the furnace draws in air to heat. It can quickly become dirty, filling with:

• Dust
• Pet dander
• Dead skin cells
• Mold spores
• Other particles and contaminants

If the filter clogs, it will restrict airflow to the heat exchanger, causing the system to overheat. As a result of the overheating, the ignitor will turn off. 

#5 Thermocouple or Ignition Sensor

Older gas furnaces have standing pilot lights with a safety mechanism called a thermocouple. The component detects heat from the pilot light. If it doesn't sense any heat, the thermocouple will kick in to shut off the gas supply, a safety measure to prevent a gas leak. 

New furnaces have ignition sensors that do the same job. Any problem with a thermocouple or ignition sensor will cause furnace ignition problems. 

#6 Filthy Gas Burners

If your gas furnace won't stay lit, its burners could be dirty. Debris accumulation will prevent the burners' flames from reaching the appropriate height or burning evenly. 

In this case, your furnace overworks to reach the desired temperatures, which can lead to premature ignition failure.

Turn to the Experts for Reliable Furnace Repair

Don't let furnace ignition failure leave your household in the cold—count on the HVAC and electrical expertise of Professional Services. The crew can quickly identify your heating system's ignition problem and provide a long-term, cost-effective solution.

Whether you want to learn the difference between a furnace and a boiler or get repairs at a moment’s notice, Professional Services offers 24/7 availability. Call (262) 214-5718 today for services throughout Southeastern Wisconsin!