• Be sure your burner is adjusted properly. A burner that is firing too rich (too high gas/air ratio) will waste gas. Set up the burner with the correct gas pressure and combustion airflow rate as stated in your equipment manual. Adjust the burner so you see blue flame with only slight yellow.
  
• Keep filters clean. Dirty combustion filters, inlet air filters and recirculation air filters greatly reduce energy efficiency by restricting air flow, disrupting the oven balance, and causing the burner to fire improperly.
  
• Clean the recirculation and combustion blowers. When blowers become dirty, they do not move air efficiently. A dirty recirculation fan takes more time and energy to heat product.

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• Related Article:
  How to Cut Oven Operating Costs