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How to correct:
Yellow tipping is caused by a lack of enough primary air. This condition may be due simply to
an incorrect air shutter adjustment. If this is the case, open air shutters to get rid of the yellow
tips. Make sure that this added primary air does not cause lifting of flames or flashback.
Lint and dust may have blocked the primary air openings, or collected inside the burner tube or
on the underside of burner ports to which reduced primary air injection, causing yellow tipping.
If so, clean and re-adjust the burner.
A burner orifice spun out of line will reduce primary air injection. Faulty drilling or a dirty orifice
can have the same effect. Check the orifice, clean it, re-align it or replace it if necessary.
5.
FLUCTUATING FLAMES:
How to recognize:
Length of burner flames may fluctuate or shorten over a period of time without any re-
adjustments of the burner. This condition usually indicates a non-uniform gas pressure at the
orifice. Fluctuating flames usually do not create any immediate problems, such as incomplete
combustion, unless flames impinge on cool surfaces. This condition should be corrected, however,
since it warns of possible future problems.
How to correct:
Unsteady gas pressures cause flames to fluctuate. Usually this condition indicates problems with
the gas pressure regulator, the gas meter or other gas supply problems. Burner flames may
shorten with no change in gas pressure or primary air adjustment. Check the orifice for blockage
by dust or dirt from supply lines. Very small pilot orifices are quite prone to blockage.
6.
FLAME ROLL-OUT:
How to recognize:
When the condition known as flame roll-out occurs, flames roll out of the combustion chamber
openings when the burner is turned ON. Flame rollout may create a fire hazard, or scorch
appliance finishes, burn wire, or damage controls. The gas in the burner mixer may be ignited,
producing a flashback.
How to correct:
Flame rollout is actually a variation of floating flames, with flames reaching for air outside the
combustion chamber. Again, the basic cause is a lack of combustion air. This lack of air may be
due to overrating of burners, poor draft or blockage of flue-ways. Apply the corrections for these
problems listed for floating flames.
7.
FLOATING FLAMES:
How to recognize:
The difference between floating flames and lifting (or blowing flames should be clearly
understood. Both conditions are undesirable, but the cause and corrective steps are different in
each case. Lifting or blowing flames are well defined and hard, and may create a blowing noise.
Cutting back on primary air usually stops flames from lifting. Floating flames are lazy looking.
They do not have well defined cones, and appear to be "reaching" for the air. They are long, ill-
defined, quiet flames which roll around in the combustion chamber sometimes completely off
the ports. Usually a strong aldehyde odor is present. Floating flames almost always indicate
incomplete combustion. They point to a dangerous condition which requires prompt correction
If secondary air supply is reduced too far, burner flames will float. Combustion products above
the burner re-circulate lower in the chamber. These products contaminate the air supply, adding
to the problem.
How to correct:
A lack of combustion air causes burner flames to float. Several conditions, or a combination of
these conditions, can be the cause. The appliance may be overrated. If so, the flue outlet area
provided for the rated input may be too small for the increased gas rate. Check the appliance
rate and reduce it if necessary.
Other conditions may cause poor venting and lead to floating flames. Soot or dust may be
blocking the flue-ways. Check flue-ways and clear any blockage found. Determine, if possible,
the reason the flue-ways were blocked up. Check for blockage of burners, and clean them if
necessary. Adjust primary air to get rid of any yellow tipping which may have produced soot to
block the flue-ways. Make sure secondary air inlet openings are not blocked.
Reduce natural draft (venting) through an appliance may take place when it is operated from a
cold start.
Some floating flames may appear for a brief moment until such time draft is
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