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
*** 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: [Example heating system inspection report topics] Caution At the ___ appliance, the gas burner flame was
... 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 orfice,
... spilling out of the burner area,
indicating a possible malfunction of this equipment.
Any of these conditions is potentially very dangerous and needs prompt attention. You should have your utility company or service person check the appliance immediately.
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 mis-adjusted or blocked air intake at a gas burner will also change the flame color and pattern.] Thanks to Charles or Mike Trumbature for suggesting this comment.
Details about gas flame color and diagnostic suggestions are at FLAME COLOR, BLUE vs YELLOW COMBUSTION.
What does the presence of rust or debris mean when found on a gas burner?
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.
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.
source: http://inspectapedia.com/plumbing/gasfaults5.htm
http://www.eastbaygaslines.com