Draft reading over the fire for flame retention on a residential oil burner?

Draft reading over the fire for flame retention on a residential oil burner?

• A. positive .02
• B. negative .02
• C. negative .20
• D. 0.00

Answer: (B)

A small negative draft above the flame is what helps keep the flame anchored and stable in an oil burner. This slight suction, about −0.02 inches of water, draws combustion gases upward and prevents the flame from wandering or being blown out by disturbances in the burner. It provides just enough air movement to maintain flame retention without pulling so much air that the fuel-air mix becomes too lean or the flame becomes unstable. If the draft were positive, air would push into the flame area and could push the flame out or cause erratic behavior. If it were too negative, such as around −0.20 inches, the flame could be starved of appropriate mixing or become unstable due to excessive suction. A zero reading offers no assist for keeping the flame in place and is more prone to instability.

A small negative draft above the flame is what helps keep the flame anchored and stable in an oil burner. This slight suction, about −0.02 inches of water, draws combustion gases upward and prevents the flame from wandering or being blown out by disturbances in the burner. It provides just enough air movement to maintain flame retention without pulling so much air that the fuel-air mix becomes too lean or the flame becomes unstable. If the draft were positive, air would push into the flame area and could push the flame out or cause erratic behavior. If it were too negative, such as around −0.20 inches, the flame could be starved of appropriate mixing or become unstable due to excessive suction. A zero reading offers no assist for keeping the flame in place and is more prone to instability.