750-204
Profire D/LND
1-3
1.5 — Combustion Air Handling System
1.5 — Combustion Air Handling System
The combustion air handling system consists of three major components:
FIGURE 1-1. Damper, Impeller, and Stator Cone
1.6 — Firing Rate Controls
Regardless of the fuel used, burner input is fully modulated between low fire and high fire on boiler demand. The
firing rate is controlled by the potentiometer-regulated modulating motor. The combustion air control damper, oil
Component Details
Damper Assembly A rotary damper regulates the combustion air volume and is positioned by a
modulating motor. The damper is normally almost closed in the low fire
position and opens as the burner drives toward a high fire position.
Motor Driven Impeller The diameter of the impeller determines available air pressure and the
width determines air capacity in cubic feet per minute. Alternate motor-
impeller combinations are available for 50 cycle or 60 cycle power and for
firing against either moderate or high furnace pressure. At altitudes up to
2,000 ft. above sea level, model “S” impellers are recommended for up to
1.5” W.C. furnace pressure. Model “P” impellers are recommended for fur-
nace pressures from 1.5” to 4.0” W.C. For higher altitudes and higher fur-
nace pressure, motor and impeller combinations are determined at the
factory.
Stator Cone The stator cone in the air housing transforms the rotating air velocity pres-
sure to static pressure prior to air entry into the blast tube.
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