To adjust the air ratio for different firing rates in an adjustable head burner, you should?

In an adjustable head burner, to optimize the air-to-fuel ratio for different firing rates, moving the head forward or backward is a key method. This adjustment directly influences the mixing of air and fuel, enhancing combustion efficiency and ensuring proper flame characteristics based on the specific firing rate required.

When the burner head is moved forward, it can create a narrower flame pattern, which is beneficial for higher firing rates. Conversely, moving it backward may widen the flame pattern, suitable for lower firing rates. This flexibility allows the burner to be fine-tuned, accommodating various operational demands while maintaining efficient combustion.

The other options do not effectively achieve the desired adjustment of the air ratio for different firing rates. While increasing oil flow could potentially impact combustion, it does not directly address air ratio adjustments in the same manner as physically repositioning the burner head. Changing the fuel type can affect combustion properties but does not yield direct air-to-fuel adjustments. Altering the combustion chamber would influence overall system design, not just the burner settings for specific firing rates. Therefore, adjusting the burner head position is the most practical and effective means to achieve the right air ratio for different firing rates.