A loud boom or bang when your furnace turns on is alarming and potentially dangerous. Learn about delayed ignition and how to fix it.
Delayed Ignition Explained
If your furnace sounds like a small explosion when it starts, it is likely experiencing "delayed ignition." This occurs when gas builds up in the combustion chamber before the ignitor successfully lights it.
What Causes the Delay?
- Dirty Burners: Rust, dirt, or spider webs can block the gas ports on the burners, preventing the gas from reaching the ignitor immediately.
- Faulty Ignitor: A weak or failing ignitor may not spark strongly or quickly enough to light the gas as soon as the valve opens.
- Improper Gas Pressure: Too much or too little gas pressure can affect the ignition timing.
A Serious Safety Issue
Delayed ignition is dangerous. The mini-explosions can crack the heat exchanger, leading to carbon monoxide leaks. If your furnace goes "boom," turn it off and call a professional immediately.
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