What determines an oil burner rating?

• A. Nozzle size
• B. Burner color
• C. Fuel price
• D. Age of boiler

Answer: (A)

The main idea is that an oil burner’s rating is the amount of heat it can deliver, which comes from how much fuel is actually fed into the burner. The fuel flow is set by the nozzle size—a larger nozzle lets more oil through at the same pressure, increasing the firing rate and the BTU output. That’s why the nozzle size determines the burner rating: it directly controls how much fuel is burned each hour.

Context helps: burner rating is typically expressed as gallons per hour or BTU per hour, and the nozzle is chosen to match the boiler’s heating needs and the system’s pressure and air supply. If you change the nozzle to a larger size, the rating goes up; a smaller nozzle reduces it. If the nozzle is wrong for the burner and boiler, combustion can be uneven or inefficient.

Other factors don’t set the rating. The color of the burner is cosmetic and has no effect on performance. Fuel price is an economic factor, not a physical characteristic of the burner. The age of the boiler doesn’t determine the burner's rated output, though aging components can affect efficiency or reliability.