750-204
Profire D/LND
4-1
CHAPTER 4 Adjustments
4.1 — Overview
While each burner is tested at the factory for correct operation before shipment, variable conditions such as
burning characteristics of the fuel used and operating load conditions may require further adjustment after instal-
lation to assure maximum operating efficiency.
Prior to placing the boiler into initial service, a complete inspection should be made of all controls, connecting
piping, wiring and all fastenings such as nuts, bolts, and setscrews to be sure that no damage or mis-adjust-
ments occurred during shipping and installation.
A combustion efficiency analysis made during the initial startup will help to determine what additional adjust-
ments are required in a particular installation.
4.2 — Combustion Adjustment on Gas and Oil
Efficient combustion cannot be properly judged by flame appearance, although it may help in making preliminary
settings.
The proper settings of air-fuel ratios must be determined by flue gas analysis. Combustion gas analysis indicates
the air to fuel ratio and the degree of complete combustion. Instruments are available to measure carbon dioxide
(CO
2
), oxygen (O
2
), and carbon monoxide (CO).
4.2.1 — Stack Temperature
Net stack temperature is obtained by subtracting the ambient temperature from the flue gas temperature. A high
net stack temperature indicates wasted heat. Stack temperature should be as low as possible without causing
flue gas condensation.
Stack heat loss can be reduced by decreasing either the temperature or the volume of the flue gas, or both. Flue
gas temperature is reduced by improving heat transfer or by reducing excess combustion air. A certain amount of
excess air is necessary to complete combustion. More efficient burners require minimum excess air.
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