Honeywell 51370B Manal page 37

Maintenance continued-
5. Annually remove the inner door and main burner assembly to clean orifices
and related parts of any dirt or other foreign material. Inspect the burner
ports for obstructions or debris and clean with a wire brush as needed.
Wire brush and/or vacuum clean the combustion chamber as needed to
remove scale deposits and debris. NOTE: It is imperative for proper
operation of the water heater that the inner door be replaced in the original
location.
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