Bradford White M1TW40S Series Service Manual page 15

Burner Inspection and Air Shutter Adjustment.
At periodic intervals (every 6 months) a visual inspection should be made of the pilot and main burner for proper
operation and to assure no debris is accumulating.
Pilot flame should be stable, some causes for an unstable pilot flame are:
a) Water heater vent is less than the allowable vent length.
b) Gas pressure is out of specification.
c) Pilot flame not fully engulfing spark/flame sensor.
Main burner should light smoothly from pilot and burn with a blue flame with a minimum of yellow tips.
Steel burner models self adjust air to gas ratio mixture and do not have an adjustable air shutter. Cast iron burner can
have the gas and air mixture properly proportioned by adjusting the air shutter on the mixer face of the main burner
(see cast iron burner adjustment below).
Main burner must be free from any debris accumulation that may effect burner operation (see burner cleaning
procedure on page 16).
Cast Iron Burner Air Shutter Adjustment
Inner door and burner components may be HOT when performing this operation. Take
Step 1. With main burner in operation, remove outer jacket door and inner door per service procedure XIII on
page 34.
Step 2. To adjust for proper burning, loosen the air shutter nut, rotate the air shutter to close the opening in the
burner, then slowly rotate the air shutter open until flame becomes as blue as possible with a minimum of
yellow tips. Tighten the air shutter nut.
Too much air will cause the flame to lift off the burner ports and create noisy burner operation.
Too little air will result in soot formation.
Step 3. Reinstall inner door and observe burner operation. Burner should operate as adjusted in step 2. If not,
repeat air shutter adjustment compensating for proper burner operation with inner door closed.
WARNING
necessary precaution to prevent personal injury.
Air Shutter
Air Shutter
TTW SERVICE PROCEDURE I
Burner Operation Inspection,
Adjustment, Cleaning and Replacement
Air Shutter Nut
Air Shutter Nut
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