Is your furnace stuck in lockout mode? Contact SM Mechanical Services for a heating system inspection in Glastonbury today.
The last thing you want to deal with during the winter is a furnace that won’t stay on or respond to the thermostat. Many problems contribute to a furnace’s inability to produce heat, including hard and soft furnace ignition lockouts. Exactly what causes a soft lockout on a furnace, and what can you do about it?
As the furnace repair experts in Glastonbury, SM Mechanical Services understands the importance of having a fully functional furnace to last through Connecticut’s freezing winters. Here, we explain soft furnace lockouts and other essential details for a heating unit experiencing this problem.
Definition of a Furnace Ignition Lockout
A furnace ignition lockout prevents the heating system from facilitating its combustion process to generate heat due to safety precautions. Heating units have sensors that detect hazardous conditions. When something triggers one of them, the furnace controller will turn off the heating system’s power and fuel for safety.
The furnace controller monitors various components, like:
- Pilot light
- Natural gas pressure
- Ventilation system
- Igniter
- Blower door
Each component must be in safe operating condition to avoid tripping the furnace controller sensor. If the furnace controller sensor deems something is unsafe due to its sensors, it will either stop additional ignition cycles or leave the blower motor running continuously.
A lockout reset is necessary to resume the furnace’s operations; furnace ignition lockouts don’t fix themselves over time. If a sensor detects a hazardous condition, you won’t have any luck turning the furnace back on until you reset it from its locked state.
Causes of a Furnace Ignition Lockout
So, causes a soft lockout on a furnace? Here are the most common reasons for a lockout:
- Damaged Igniter: A furnace igniter should activate within seconds of the furnace turning on. Otherwise, the flame will be undetectable by the flame sensor, and the controller will prevent the furnace from starting. After three times of trying to get the furnace on with a faulty igniter, it will go into lockout mode.
- Defective Flame Sensors: If the igniter works but the flame sensor is faulty or dirty, it won’t detect the flame regardless of its timing. Most modern furnace models will allow two start-up attempts before locking down the furnace.
- Limit Switch Response: The limit switch monitors fuel pressure and heat exchanger temperatures. When temperatures go out of range or the fuel pressure drops, the switch closes and puts the furnace into lockout mode. Restricted airflow from dirty filters also trips limit switches.
Differences Between a Hard and Soft Lockout on a Furnace
Furnace ignition lockouts fall into two categories. The first category is a hard lockout that causes the furnace controller to cease the ignition sequence under real or perceived hazardous operating conditions. It usually happens after several attempts of starting the heating system without fixing the problem that keeps tripping sensors and the furnace controller.
A soft lockout is a partial furnace shutdown. If you can identify the source of the unsafe condition the sensors are picking up on, you can safely restart your furnace while it’s in a soft lockout. Unfortunately, you’ll need an HVAC technician to reset your heating system manually if your soft lockout becomes a hard lockout.
How to Identify the Cause of a Lockout
Your furnace will let you know the source of your lockout problem if you know where to look. Most modern systems have some type of display that shows an error or status code. For example, an older furnace might produce a sequence of flashing lights that accompany a specific error code, while updated equipment show easily readable alphanumeric codes on digital screens.
When you determine how your furnace presents its lockout problem code, write it down and refer to your owner’s manual to see what problem the code corresponds to. These codes will give you an idea of what could be affecting your furnace’s operations.
Still, it’s best to contact an HVAC technician who routinely performs furnace inspections. They can pinpoint the exact problem and fix it accordingly. They can also identify other issues that could reduce your heating system’s performance, energy efficiency, and lifespan.
How to Reset a Furnace in Lockout Mode
Resetting a furnace in lockout mode might seem simple, but it can be complicated. It requires a lot of experience and HVAC expertise. You would also have to ensure you resolve the problem causing the lockout and ensure the system is in lockout mode and not experiencing another issue that’s preventing it from working correctly.
It’s also helpful to clean or replace your air filters before resetting your furnace. Dirty filters can restrict airflow through the HVAC system and cause problems with the limit switch that could lead to a lockout. Inspecting your vents and air ducts for damage and blockages is also a good idea.
When you’re ready to reset a gas furnace and get it out of lockout mode, you must turn off the power for about 20 seconds before switching it back on. If your furnace is an older model, you might have to wait up to two hours before turning your equipment on.
If the reset doesn’t work, there might be an underlying problem preventing the heating unit from resuming its operations safely. In that case, reach out to a knowledgeable HVAC company to repair or replace your furnace.
Get a Detailed Furnace Inspection from the Professionals at SM Mechanical Services
If your furnace pilot light won’t stay lit or is in need of an annual tune-up, you can rely on the HVAC experts at SM Mechanical Services. As a BBB-accredited business, we offer everything from furnace repairs to oil to natural gas conversions for boilers. Our skilled and trained technicians service all HVAC makes and models with the utmost care, helping us earn nearly 200 five-star reviews.
Are you still wondering, “What causes a soft lockout on a furnace?” Call (860) 530-2632 to request an appointment with SM Mechanical Services to ensure your furnace’s functionality and performance.