Water Heater Won’t Stay Lit? Check This First!

“ Don’t Get Burned “ : Beware of companies that claim you need a new water heater when there may be a simple fix.

The Overlooked Reason Your Gas Water Heater Keeps Failing

Introduction: The Frustration of a Fickle Water Heater

It’s one of the most common and annoying home maintenance problems: you step into the shower expecting hot water, only to be met with a blast of cold. You check the gas water heater, and sure enough, the pilot light is out again. Or perhaps the main burner ignites, runs for just a few minutes, and then shuts itself off, leaving you in the same predicament.

What could be causing such a persistent and frustrating failure? While several issues can affect a water heater, the answer is often a simple, overlooked maintenance task related to a critical part your heater needs to "breathe."

1. Why Your Water Heater Needs to Breathe

Just like a campfire needs a steady supply of air to keep burning, a gas water heater requires a constant flow of oxygen for its pilot light and main burner to operate correctly and efficiently. Without sufficient air, the gas cannot combust properly, leading to ignition failures and shutdowns.

This vital process is more sophisticated than you might think. According to service manuals, air for combustion is drawn into the water heater through openings in the jacket. This air travels down and around the combustion chamber and enters through holes in the very bottom. From there, it travels up through the internal flame arrestor (sometimes called a spark arrestor), where the velocity of the air is increased and its direction is altered before it mixes with gas for the burner.

This internal flame arrestor is a screen-like safety component at the base of the combustion chamber. On some models, it works in tandem with a removable, external filter—either a "snap-in style filter" or a "wrap-around style filter"—that serves as the first line of defense against debris.

2. The Hidden Culprit: A Clogged Flame Arrestor

Because the water heater's air intake system draws from the surrounding area, it inevitably pulls in airborne debris like dust, lint, and pet hair. This can be especially problematic if the unit is in a laundry room or a dusty garage. When the external filter becomes clogged or is missing, this debris is pulled directly into the unit, clogging the internal flame arrestor screen and starving the burner of oxygen. Additionally, an expert would note that over many years, rust can fall from the inside of the tank and accumulate on the burner assembly, contributing to airflow issues.

This lack of air is a direct cause of many common water heater failures. As one person troubleshooting this exact issue was advised by the factory:

"Your flame arrestor is clogged and dont have enough combustion air for the spark to ignite"

This simple diagnosis gets to the heart of the problem. When the burner is starved of oxygen, it cannot ignite or sustain a flame, leading to the symptoms that leave you without hot water.

3. Telltale Signs of an Airflow Problem

Before you suspect a costly failure of the gas control valve or thermocouple, check for these telltale signs of simple airflow starvation. Because a clogged flame arrestor can cause a variety of symptoms that mimic more complex component failures, identifying them can save you from a premature, expensive service call.

• The pilot light goes out randomly or will not stay lit after being ignited.

• The main burner shuts off just a few minutes after it fires up.

• The igniter fails to create a spark when the gas control knob is depressed for gas to flow to the pilot.

4. More Than an Inconvenience: It's a Critical Safety System

The flame arrestor does more than just let air in; it is a key component of the water heater's Flammable Vapor Ignition Resistant (FVIR) safety system. All modern residential gas water heaters are required to meet FVIR standards.

In simple terms, the FVIR system is designed to prevent flames inside the combustion chamber from igniting any flammable vapors that might be present in the air outside the water heater. Manufacturers explicitly state the system is engineered to handle vapors from substances like gasoline, paint thinner, or other chemicals. The flame arrestor allows air to enter but prevents the flames from traveling backwards and igniting vapors outside of the unit, which could cause a fire or explosion. Keeping this component clean is therefore essential for the proper and safe operation of this critical feature.

Conclusion: A Clean Arrestor is Required for a Reliable and Safe Water Heater

A steady, unobstructed supply of air is essential for your gas water heater's performance and safety. A dirty external filter and clogged internal flame arrestor are common but frequently overlooked causes of pilot light and burner failures.

Keeping the flame arrestor system free of dust and debris is vital for two key reasons: it ensures you have reliable, consistent hot water, and it maintains the integrity of the unit's built-in fire and explosion prevention systems. To avoid problems, manufacturers recommend a visual inspection of the flame arrestor and air intake areas every 6 to 12 months to ensure your water heater continues to operate properly and safely.