Explore Common Water Heater Burner Flame Problems and Repair Tips

Understanding the color and shape of the water heater burner flame is crucial for ensuring the safe and efficient operation of your water heater.

The condition of the burner flame can reveal a lot about the health of your water heater.

This guide talks about the most common problems associated with incorrect gas burning, how to identify them, and the steps you can take to rectify these issues.

Additionally, we'll explore what a normal water heater burner flame should look like, helping you maintain your appliance in top condition. We will also address the following questions:

  • Why checking the water heater burner flame's color and shape is important?
  • What should you do if the flame has a yellow, orange, or blue glow?
  • What are the most common problems if the gas is not burning correctly, and how to avoid them?
  • How does the normal flame color and shape look?

Should I see a flame in my water heater?

Whether or not you should see a flame in your water heater largely depends on the type and model of the heater.

In traditional gas water heaters, a visible flame is a normal and necessary part of operation.

However, for electric water heaters and some advanced gas models, there will be no visible flame as they use heating elements or other technologies to heat the water.

It's important to understand your water heater's functioning and consult the user manual or a professional if you're unsure about what is normal for your specific model.

The role of flame in gas water heaters

Every gas-powered, tank-type water heater employs a gas burner located in the combustion chamber to heat water, using either a pilot light or an electrode to ignite the fire, and a gas control valve to regulate the flow of natural gas or propane.

During the burning process, exhaust gases are expelled, either through natural convection or with the aid of an electric blower. As a result, tank-type water heaters are categorized into atmospheric, power vent, direct vent, and power direct vent models.

Most models feature a viewport at the bottom of the unit, allowing users to check the condition of the gas burner, observe the appearance of the flame, and determine whether any action is needed.

What should water heater flame look like?

Blue flame

blue flame on the gas burner

In gas water heaters, the flame type is a critical indicator of the unit's health and efficiency.

The most common and ideal flame type is the blue flame.

A steady blue flame indicates complete combustion, meaning the gas is being used efficiently and safely. This blue color results from the adequate mix of gas and oxygen, leading to a hotter, more efficient flame that ensures optimal heating performance.

A blue flame also minimizes the production of harmful byproducts like carbon monoxide, making it a safer option.

Yellow flame

yellow flame on the gas burner

On the other hand, the yellow flame in a gas water heater is cause for concern. This color typically indicate incomplete combustion, often due to a lack of sufficient air or an excess of contaminants in the gas.

Incomplete combustion is not only less efficient but also potentially dangerous, as it can lead to the production of carbon monoxide and other harmful gases.

Additionally, yellow flames can result in soot buildup, which further reduces the efficiency of the heater and can cause additional maintenance issues.

In such cases, it's essential to address the issue promptly, either by adjusting the air-to-gas ratio or seeking professional assistance to ensure the heater's safe and efficient operation.

Orange/red flame

red flame on the gas burner

An orange or red flame in a gas water heater is also indicative of potential issues and warrants attention.

Like a yellow flame, an orange flame can suggest incomplete combustion, often caused by a lack of sufficient air flow or an excess of contaminants. This orange hue might be due to the presence of rust, dust, or other debris in the burner, which disrupts the flame's purity and can lead to inefficient heating.

A red flame, while less common, can indicate even more serious problems. It may be a sign of very poor combustion, potentially caused by a severely obstructed air flow or a significant imbalance in the gas-to-air ratio. This condition not only reduces the heater's efficiency but also poses a risk of producing higher levels of carbon monoxide and other harmful gases.

Both orange and red flames are signs that the water heater is not operating correctly and may not be safe. It's important to address these issues promptly. Cleaning the burner and ensuring proper ventilation can sometimes resolve the problem.

However, if the issue persists, it's crucial to consult a professional to diagnose and repair the heater to prevent potential safety hazards and ensure it operates efficiently.

Preventing accidents

Most of today's gas water heaters are equipped with FVIR (Flammable Vapor Ignition Resistant) technology and a unique flame-arrestor feature. This technology prevents flames and burning vapors from escaping the combustion chamber, thereby reducing the risk of open fires and potential explosions. Water heaters that are susceptible to these issues often exhibit discoloration on the flame arrestor, indicating the need to replace the unit.

Some gas water heaters come with an air shutter, allowing for the adjustment of the air-to-gas mixture to ensure proper burning.

Excessive air can cause the burner flame to lift off the burner ports, resulting in noisy burning. Conversely, a lack of sufficient air leads to incomplete gas combustion, which can result in sooting.

The manually adjustable air shutter is commonly found on cast iron burners, whereas steel burners typically use a self-adjusting air mixture system.

Proper gas combustion and burner flame

The primary indicators of proper gas combustion are a stable blue flame or a blue flame with yellow inner cones, as shown in the picture.

For optimal operation, it's essential to ensure a sufficient supply of air and adequate ventilation. The venting and exhaust systems must remain unobstructed. In atmospheric-type water heaters, fresh air is typically delivered through wall provisions. These provisions must be installed in accordance with codes and the manufacturer's instructions to ensure safe and efficient functioning of the water heater.

Testing for the proper draft

A correctly formed burner flame in a water heater also depends on adequate draft in the draft hood, so regular check-ups are recommended. An easy method to test this is by using a match or candle flame, or smoke, and placing it close to the draft hood. If the steady flame or smoke is drawn into the opening, it indicates that proper draft is established.

If the match flame flutters or is blown out, it suggests that the products of combustion are not correctly venting through the system but instead escaping into the surrounding area, contaminating the air. These changes are also visible in the burner flame, as it may change its color to yellow or orange, and its stable pattern becomes unstable; it appears lazy or lifts off the ports.

Troubleshooting and resolving common water heater burner flame issues

Water heaters are a cornerstone of modern home comfort, providing the essential service of hot water on demand.

However, like any complex appliance, they can encounter issues, particularly with the burner flame, which is vital for their efficient operation.

Here are some of the common problems that can afflict the flames in gas water heaters and how to solve them:

The burner flame is yellow and lazy resulting in smoking and sooting (carbon formation)

  • Remove the scale buildup from the top of the gas burner.
  • Insufficient air might be an issue, so ensure proper ventilation for the water heater.
  • If the flue or vent system is blocked, identify the cause, clean the pipes, and remove the blockage.
  • A proper supply of combustion air is crucial, especially if the water heater is located in a closed or confined area.
  • If the main burner or burner orifice is clogged, they should be unclogged or replaced as necessary.
  • Excessive heat build-up inside the chamber can cause the thermal switch to trip, shutting down the entire water heater. A burner flame with a yellow glow is the primary cause of excessive smoking and sooting in the combustion chamber, flue tubes, and gas burner. These issues can disrupt the normal operation of the water heater, damage the unit, and pose a risk to your safety.

emergency plumber

The burner flame floats and lifts of ports (fluctuates)

  • The orifice on the main burner may be too large; replace it if necessary.
  • Clean the venting system and ensure air and flue passageways are free from deposits and debris.
  • If high gas pressure is suspected, contact your utility company.
  • Check for water in the gas line, which could be due to pipe corrosion.
  • Address issues related to cold or excessive draft by identifying and fixing the root cause.
  • If the water heater is receiving too much air, adjust the air shutter to reduce air supply.
  • Verify that the flue vent is correctly connected to the water heater and reconnect it if necessary.
  • Inspect the gas valve and replace it if there's a problem, rather than attempting to repair it.

Note: If an older water heater has an unstable flame and the problem cannot be identified, consider installing a new gas unit, especially if other gas appliances on the same line are operating without issues.

The burner flame is noisy

  • Adjust the air shutter to reduce the air supply if the water heater is receiving too much air.
  • Contact the utility company to check if the heater is experiencing high gas pressure.
  • Address and correct any issues related to excessive draft.

The burner flame is too high

  • If you suspect high gas pressure, consult with the utility company.
  • Ensure there is a secure connection between the water heater and the flue.
  • If the air supply is insufficient, increase the amount of air to the heater.


Sooting is caused by incomplete combustion and can be identified as a black substance composed mainly of carbon particles. This soot can accumulate on the elements of the heater, impacting its regular operation and potentially affecting your health. In addition to natural gas burners, this issue can also occur in propane heaters if incorrect components (such as the orifice) or gas regulators are used.

Since sooting indicates improper heating operation and poses health risks, it's important to contact a local water heater expert to resolve the issue.


It is essential to remember the importance of maintaining an adequate supply of both combustion and ventilating air, free from any obstructions, for the safe and efficient operation of your water heater.

Insufficient air supply can lead to the recirculation of combustion products, contaminating the surrounding air and posing health risks.

As highlighted, one of the primary indicators of improper gas combustion is a noticeable change in the flame's pattern, color, shape, and height.

Regular visual inspections of the main burner, burner flame, and pilot light, ideally every six months, are crucial.

These inspections should be complemented by cleaning any dust and debris from the gas burner and combustion chamber, ensuring the longevity and safety of your water heater.

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