Photograph of  this gas flame which gives a clue that there may be an operating problem and an unsafe gas furnace in this building Gas Appliance or Gas Heater Flame & Noise Defects

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Gas burner operating defects & noises:

Here we provide descriptions and photographs of unsafe gas piping, indications of unsafe or improperly operating gas appliances, gas meters, and other gas installation defects are provided.

We discuss how to diagnose and how to report defects found in oil or gas piping inspections. We include inspection report language examples for gas heating appliance flame & noise problems & hazards.

This article includes example home inspection or gas appliance inspection report language for reporting defects in gas piping & burner operation at heaters, ranges, ovens, water heaters or similar LP, propane, or natural-gas fired appliances.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Gas Flame & Noise Defects - How to Identify & Report Other Defects in LP or Natural Gas Appliances by Examining the Gas Burner Flame or Burner Noises

Solid gas flame at the burner of a Cal-o-Rex glass lined LP gas water heater in Pozos, Guanajuato, Mexico. The flame dispersing cone is damaged. (C) Daniel Friedman (2015)Gas Burner & Flame Color Interpretation


[Click to enlarge any image]

Our gas flame colour illustration at page top illustrates a questionable irregular gas flame at the burner of a gas-fired heating furnace.

Looking into three burner ports of this heater we see three very different burner flames, suggesting perhaps a debris-blocked burner tube or improperly-adjusted air shutters, or (less likely) a partly-blocked gas metering orifice.

Above we see the gas flame in a Cal-o-Rex Dur-A-Glas LP gas fired water heater installed in Pozos, Guanajuato. This water heater (geyser) was made in 1999 so we're looking at a water heater gas burner after sixteen years of use.

The photo offers a view of a damaged gas burner flame dispersing cone and also of the passage of gas combustion products up through the center flue of this calorifier. The flame colours are normal, mostly blue with yellow tips.

Comparing colours of gas flames: yellow = unhealthy, yellow tips = normal for LPG or propane, soft blue flame = normal for natural gas (C) Daniel Friedman adapted from Bosch (2014)

Our gas flame colour illustration shown above, adapted from Bosch (2014), shows how you might distinguish among the properties of the following:

Gas cooktop flame color check (C) Daniel Friedman

What the Bosch drawing and our photo do not show are other gas burner flame defects such as noises, flame lifting off of the burner, flame jumping excessively, flame uneven, or blocked at some orifices by debris or spills or lastly and particularly dangerous, the presence of soot - an indication of a serious even fatal carbon monoxide hazard.

Above we see a normal LP gas flame at the burner of a gas stove installed in Poughkeepsie, NY.

Also see GAS FLAME COLOR CHECK for more examples of gas flame color checks and the relationship between air mix and gas flame.

Other Example Gas Burner Inspection Points & Reporting Language

*** Safety Recommendation: gas grill we suggest keeping the gas turned off at the rubber hose connection below the rear deck as leaks could be very dangerous.

The use of rubber tubing rather than iron piping is unsafe and may not be permitted for this installation, and we suggest you review this question with your local fire inspector. Usually this is not a significant expense if correction is needed. This item should be addressed promptly.

Gas Appliance Flame Observations: Caution: examining the burner when this appliance was operating we noted that the flame was floating above the burner ports.

You should check with your utility company or heating appliance service person. Possible causes include high gas pressure, clogged flue, inadequate air supply, excessive or very cold drafts.

Gas Appliance Flame Observations & Reporting checklist: [Example heating system inspection report text is below]

At the ___ appliance, the gas burner flame was [example gas flame defects]

___ yellow and lazy [inadequate gas pressure or inadequate combustion air],
___ unusually high [possibly excessive gas pressure],
___ making a popping noise when turned off and on,
___ burning at the orifice,
___ spilling out of the burner area,

indicating a possible malfunction of this equipment.
Any of these LP gas , propane, or natural gas burner conditions is potentially very dangerous and needs prompt attention. You should have your utility company or service person check the appliance immediately.

Immediate LP or natural gas safety hazards: if there is evidence of an LP or natural gas leak at a building, gas odors, for example, you should:

Sooty gas burner (C) Daniel Friedman

Watch out: General safety warning: improper installation and even improper inspection and testing methods involving natural or "LP" gas can involve dangerous conditions and risk fire or explosion.

If you smell gas you should leave the building immediately and should do so without doing anything that could create a spark such as operating a light switch or telephone. From a safe location, call your gas company's emergency line and/or your fire department.

Watch out: soot observed on or around an LP or or natural gas burner can be a sign of extreme danger. Normally gas fired appliances run rather clean and with no soot deposition.

But if there is a combustion air problem a system can soot up and even completely clog a flue with soot very quickly - in minutes or hours. The risk is potentially fatal carbon monoxide poisoning of building occupants.

The text provided here is a working draft and may be incomplete or inaccurate. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. NOTICE: while example report language is provided here, reproduction of this or any of our web pages or their contents at other websites or in printed documents for sale is prohibited.

What should a gas furnace or boiler gas burner flame look like?

When properly adjusted the gas burner for a 100,000 BTU gas furnace or gas boiler, will have a flame about 1" or so high. The top of the gas flame will roll slightly 90 deg across and be blue in color.

If the gas pressure is too high you will notice the tips of the flame much higher, pointed and orange in color. The orange gas flame color usually means there is too much gas for the air mix input. [Dust, debris, or other problems in the gas/air mix ratio, such as a misadjusted or blocked air intake at a gas

More about gas flame color and diagnostic suggestions is at BLUE vs YELLOW COMBUSTION FLAMES and

More about the relationship between flame colour when burning oil or gas fuel is at COMPLETE COMBUSTION, STOICHIOMETRIC

What does the presence of rust or debris mean when found on a gas burner?

Photograph of gas burner corrosion

Excessive rusting every year usually accompanies these problems of improper gas pressure, inadequate combustion air, or wet conditions. If you vacuum a lot of rust one year and it is back the next, then there is a problem that needs to be diagnosed and corrected.

(Rust can damage a heat exchanger, cause a hole, and make the heater unsafe. Rust can also indicate general moisture conditions that could be causing other damage to or safety problems with the heater, including flue or chimney safety hazards.

Photograph of rusty gas burner

Looking for rust on a gas heater's burner is a simple, quick visual check anyone can do to see if there is cause for alarm. If rust is recurrent as we describe, further inspection is needed, and the gas pressure regulator should be checked as well.

Some of the residential gas furnaces or gas fired boilers show the correct flame patterns in their Installation and Operation Manuals.

Thanks to Charles or Mike Trumbature for suggesting this comment:

I see mostly Rheem furnaces in homes 20 - 30 years old. Rheem(TM) must have cornered the market at that time here in the Houston Texas area.

I've seen several homes in various areas with the same identical furnaces. I replaced a thermocouple on a relatively new unit once and noticed the "tame" flame pattern compared to my raging bonfire in my own furnace which was an older unit.

On my older gas furnace I was constantly cleaning out rust every year. That's when I checked the gas pressure at the gas regulator/valve and found it too high. My friend's heat exchanger still looked new, mine was a bucket of rust.


Gas Burner Manuals


Continue reading at GAS REGULATORS for APPLIANCES or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see GAS BURNER FLAME NOISE & DEFECT FAQs - questions & answers posted originally at this article




Or see GAS REGULATOR NOISES - buzzing, humming, and other noises at gas appliance regulators

Or see NOISE, WATER HEATER WHISTLE - screaming, screeching, or whistling water heater noise troubleshooting & repair.

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GAS BURNER FLAME & NOISE DEFECTS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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