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3.12.3 Gas Pressure Adjustment
See rating plate for the minimum and maximum gas pressure of the boiler. Each boiler is furnished with two plugged taps in the gas manifold for test gauge connections. One tap is located at the main gas cock for measuring the gas supply pressure (1/4” IPS). The supply pressure during main burner op- eration must be greater than the minimum indicated on the rating plate. The second tap is located down- stream from the last main gas control in the union elbow where the gas line enters the back of the cabinet and is for measuring the manifold gas pres- sure (1/8” I.P.S.)
High fire Adjustment
Gas Pressure Adjustment
To adjust the gas pressure, remove the cover plate from the air / gas ratio control valve. Set the boiler at High fire as described in the boiler operation sec- tion of the manual. The High fire gas pressure is adjusted with the lower screw of the air / gas ratio control vale. Using a combustion analyzer, adjust the oxygen reading between 6.5% and 7.5%. Set the boiler at Low fire as described in the boiler opera- tion section of the manual. For initial adjustment the cabinet pressure should be the same as shown on the “Factory Firetest” label. The Low fire gas pres- sure is adjusted with the upper screw of the air / gas ratio control valve. Using combustion measurement equipment, adjust the oxygen reading between 6.5% and 7.5%.
Run the firing rate up and down through the com- plete firing range and verify that the oxygen read- ings are within the proper range.
BASIC COMBUSTION ADJUSTMENT PROCEDURE
Start boiler in test mode
Adjust start pressure with orange cam 1.0” – 1.2” H2O cabinet air
Adjust pilot gas for good pilot – See factory run out label
Start boiler and measure combustion O2 between 6.0 – 8.0
Ramp to high fire adjust cabinet air to nameplate with red cam. Combustion O2 between 7.0 – 7.5.
Ramp to low fire 0.3” adjust cabinet air with blue cam
Check high fire and low fire again
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