Why Does My Furnace Ignite Then Go Out? Discover the Shocking Truth!
What To Know
- The cold wind howls outside, and you’re snuggled up on the couch, only to feel a sudden chill as your furnace sputters and shuts off.
- When the thermostat senses the temperature dropping below your set point, it sends a signal to the furnace.
- If the gas valve is clogged, it may not allow enough gas to flow to the burner to sustain a flame.
The cold wind howls outside, and you’re snuggled up on the couch, only to feel a sudden chill as your furnace sputters and shuts off. You hear the familiar ignition sound, but then silence. “Why does my furnace ignite then go out?” you wonder, shivering under your blanket. This frustrating situation can leave you feeling cold and confused.
Don’t worry, we’re here to help. This blog post will explore common reasons why your furnace might ignite and then go out, providing insights into diagnosing the issue and potential solutions.
The Ignition Sequence: A Quick Overview
Before diving into troubleshooting, let’s understand the basic steps involved in your furnace’s ignition sequence:
1. Thermostat Signal: When the thermostat senses the temperature dropping below your set point, it sends a signal to the furnace.
2. Gas Valve Opens: The gas valve opens, allowing natural gas or propane to flow into the burner.
3. Igniter Spark: The igniter produces a spark to ignite the gas.
4. Flame Sensor Detection: The flame sensor monitors the flame and sends a signal back to the control board.
5. Burner Operation: If the flame sensor detects a stable flame, the burner continues to operate, heating the air.
6. Air Circulation: The blower fan circulates the heated air throughout your home.
If any of these steps are interrupted, your furnace may ignite then go out.
The Most Common Culprits: A Troubleshooting Guide
Now, let’s investigate the most common reasons why your furnace might be experiencing ignition problems:
1. Dirty Flame Sensor
The flame sensor is a crucial component that detects the presence of a flame. Over time, dust and debris can accumulate on the sensor, preventing it from accurately sensing the flame.
Solution: Clean the flame sensor with a fine-grit sandpaper or a wire brush. Be sure to disconnect the power to the furnace before cleaning.
2. Blocked Air Filter
A dirty air filter can restrict airflow to the furnace, causing it to overheat and shut down.
Solution: Replace the air filter regularly, at least once a month during peak heating season.
3. Faulty Igniter
The igniter is responsible for producing the spark that ignites the gas. If the igniter is faulty, it may not produce a strong enough spark to ignite the gas.
Solution: Check the igniter for any signs of damage or wear. If the igniter is faulty, it will need to be replaced.
4. Clogged Gas Valve
The gas valve controls the flow of gas to the burner. If the gas valve is clogged, it may not allow enough gas to flow to the burner to sustain a flame.
Solution: Check the gas valve for any signs of debris or blockage. If the gas valve is clogged, it will need to be cleaned or replaced.
5. Low Gas Pressure
Low gas pressure can prevent the burner from igniting properly.
Solution: Contact your gas company to check for low gas pressure.
6. Faulty Control Board
The control board is the brain of your furnace. If the control board is faulty, it may not be able to properly control the ignition sequence.
Solution: Contact a qualified HVAC technician to diagnose and replace the control board if necessary.
7. Pilot Light Issues
In some older furnaces, the pilot light needs to be lit manually. If the pilot light is out, the furnace will not ignite.
Solution: Refer to your furnace’s manual to learn how to light the pilot light.
When to Call a Professional
While many furnace problems can be addressed with DIY solutions, it’s important to know when to call a professional HVAC technician. If you experience any of the following, it’s best to leave the troubleshooting to the experts:
- You smell gas: A gas leak is a serious safety hazard and should be addressed immediately.
- You hear unusual noises: A loud banging or clanging sound could indicate a serious problem with your furnace.
- Your furnace is leaking water: This could be a sign of a cracked heat exchanger, which needs to be repaired or replaced.
- You’ve tried troubleshooting but the problem persists: If your furnace continues to ignite and then go out, it’s best to call a professional to diagnose and fix the issue.
A Final Word on Furnace Safety
It’s essential to prioritize your safety when dealing with furnace problems. Always disconnect the power to the furnace before working on it. If you’re unsure about any repairs, contact a qualified HVAC technician.
Beyond the Basics: Additional Factors to Consider
While the above troubleshooting steps cover common issues, there are other less frequent factors that can contribute to furnace ignition problems. These include:
- Improper Ventilation: Insufficient ventilation can lead to a buildup of combustion byproducts, affecting the flame sensor and causing the furnace to shut down.
- Electrical Issues: A faulty electrical connection or wiring problem can disrupt the furnace’s ignition sequence.
- Blocked Vent Pipes: Obstructed vent pipes can prevent proper exhaust of combustion gases, leading to furnace malfunction.
- Age of the Furnace: Older furnaces are more prone to breakdowns and may require more frequent maintenance.
A Final Note: Prevention is Key
Regular maintenance can help prevent many furnace issues, including ignition problems. Schedule annual furnace inspections and tune-ups to ensure your furnace is operating efficiently and safely.
Time to Get Warm: A Look Ahead
Now that you have a better understanding of why your furnace might ignite then go out, you can take steps to diagnose and fix the problem. Remember, safety should always be your top priority. If you’re unsure about any repairs, don’t hesitate to call a professional HVAC technician. Stay warm and cozy!
Questions We Hear a Lot
Q1: How often should I change my furnace filter?
A1: You should change your furnace filter at least once a month during peak heating season. If you have pets or allergies, you may need to change it more frequently.
Q2: What does it mean if my furnace is making a loud banging noise?
A2: A loud banging noise could indicate a serious problem with your furnace, such as a cracked heat exchanger. It’s important to contact an HVAC technician immediately.
Q3: How can I prevent my furnace from igniting and then going out?
A3: Regular maintenance, including cleaning the flame sensor, replacing the air filter, and inspecting the gas valve, can help prevent furnace ignition problems.
Q4: How long should a furnace last?
A4: A well-maintained furnace can last for 15-20 years. However, older furnaces may require more frequent repairs.
Q5: Is it safe to run my furnace if it’s igniting and going out?
A5: It’s not safe to run your furnace if it’s igniting and going out. This could indicate a serious problem that needs to be addressed by a professional.