• Atomizing nozzles are available in a wide range of flow rates, all but eliminating the need for specially calibrated nozzles. Between 1.00 GPH and 2.00 GPH, for example, seven different flow rates are available. Generally, with hot water and warm air heat, the smallest firing rate that will adequately heat the house on the coldest day is the proper size to use and the most economical. Short on-cycles result in low efficiency. Another guideline is to select the flow rate that provides a reasonable stack temperature regardless of the connected load. (According to the New England Fuel Institute, aim for a stack temperature of 400°F or lower on matched packaged units or 500°F or lower on conversion burners.) If the boiler or furnace is undersized for the load, it may be necessary to fire for the load and ignore the efficiency

• Spray angles are available from 30° through 90° in most nozzle sizes to meet the requirements of a wide variety of burner air patterns and combustion chambers. Usually it is desirable to fit the spray angle to the air pattern of the burner. In todays flame retention burner, it is possible to fire more than one spray angle with good results. Generally, round or square combustion chambers should be fired with 70° to 90° nozzles. Long, narrow chambers usually require 30° to 60° spray angles.

• Burner air patterns are much like nozzle spray patterns in that they fall into the same general classifications, either hollow or solid. As you would expect, a burner with a hollow air pattern generally requires a hollow cone fuel nozzle. A burner with a solid air pattern will give highest efficiency with a solid cone nozzle, but the flame will probably be longer

Delavan .60-70AR-D