Oil Burner Nozzle Firing Rate (GPH)
The oil burner nozzle firing rate (gallons per hour) to hit a target heat OUTPUT, for swapping a nozzle or matching a boiler/furnace to a heat loss. Fuel input = output / steady-state efficiency; firing rate = input / heating value. No. 2 fuel oil ~138,500 BTU/gal (varies ~138,000-140,000, editable). For 88,000 BTU/hr output at 85% efficiency: input 88,000 / 0.85 = 103,529 BTU/hr, firing rate 103,529 / 138,500 = 0.75 GPH -> a 0.75 nozzle. A 1.00 GPH nozzle fires 138,500 BTU/hr input, ~116,300 output at 84%. Nozzles come in fixed GPH steps and spray patterns; actual flow shifts with pump pressure (rated at 100 psi, flow ~ sqrt of the pressure ratio). A sizing aid; the rating plate and firing range, the nozzle chart, the pump pressure, and a combustion analysis govern.
Formula and source
input_btu_hr = output_btu_hr / (steady_state_efficiency_pct / 100); firing_rate_gph = input_btu_hr / heating_value_btu_gal. No. 2 fuel oil heating value ~138,500 BTU/gal (editable).
Oil burner nozzle firing rate (NORA / oil-heat industry practice; EIA No. 2 distillate heating value ~138,000-139,000 BTU/gal), by name; the appliance rating plate and firing range, the nozzle chart, the pump pressure, and a combustion analysis with the manufacturer's instructions govern.
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