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IMPROPER FLAME DIAGNOSTICS
For any of the improper flames discussed, refer to the following chart for the appropriate corrective
actions. In most of the malfunctions described thus far, the burner flames will change character-
istics when a problem develops. However, there are times when the symptom of a burner problem
is an unusual noise. The noise may be a “rumbling” or “gurgling” sound or a “high pitched squeal”
or “burr.” In any event, the table lists burner noise malfunctions and their respective causes and
corrective actions.
Symptom Cause
Corrective Action
Flame is white-blue and has hard,
sharp features.
Excessive primary air.
Adjust air shutter.
Flame is small and blue in color. 1. Clogged burner orifice.
2. Clogged venturi.
3. Restricted or clogged gas line.
4. Excessive low gas pressure.
1. Clean or replace burner orifice.
2. Clean venturi. Replace burner, if
necessary.
3. Remove & clean the gas supply
line. Relace, if necessary.
4. Use a manometer and adjust the
gas pressure.
Flame is yellow. 1. Insufficient primary air.
2. Blocked primary air shutter.
3. Oversized burner orifice.
1. Adjust primary air shutter.
2. Clean primary air shutter &
adjust for proper air-gas mixture.
3. Replace burner orifice.
Flame is noisy (rumbles or
gurgles).
1. Excessive primary air.
2. Excessive gas pressure.
1. Clean primary air shutter &
adjust for proper air-gas mixture.
2. Use a manometer and adjust the
gas pressure.
1. Clean orifice. Replace, if
necessary.
2. Replace orifice.
3. Use a manometer and adjust the
gas pressure.
1. Smooth interior surface. Replace
burner, if necessary.
2. Clean mixing tube.
1. Replace pressure regulator, if
necessary.
2. Adjust regulator on control valve.
Replace, if necessary.
Orifice noise (burr or high-pitched
squeal).
Air intake or mixing noise.
Erratic burner flame (fluctuates
high to low).
1. Debris lodged in orifice.
2. Improper orifice size.
3. Excessive gas pressure.
1. Rough area in mixing tube or
venturi.
2. Loose debris in mixing tube or
venturi.
3. Burner not seated correctly over
orifice. Distance between orifice
and venturi too large.
1. Gas regulator flutter.
3. Seat burner over orifice.
2. Control valve malfunction.