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MACH
Gas Fired Boiler
3.11.2 Gas valve adjustment
The gas valve is located inside the cabinet. Each valve is labeled and adjusted for a specific fuel. See specific section
for proper application.
Check the combustion using a combustion analyzer and adjust the fuel/air ratio of the valve being used according to
the procedures below. For initial startup, the boiler should be fired and the combustion should be adjusted.
To adjust high fire:
Required Tools: Flat head screwdriver and Combustion analyzer
Start the boiler and observe proper operating parameters for the system.
Set boiler to the "BNR ON TEST HI", as described above, to achieve
maximum firing rate of the boiler. Check combustion readings using the
combustion analyzer. If combustion readings are not in accordance with
Table 3-1, adjust as follows: Open the front panel of the boiler. Locate
the automatic gas valve. Turn the orifice adjusting screw, located on the
downstream side of the valve, in the direction indicated on the sticker to
increase or decrease the gas flow. Increasing the gas flow decreases
the combustion exhaust O
, while decreasing the gas flow increases the
2
combustion exhaust O
. There will be a slight time delay between the
2
adjustment and the response of the CO
/O
measuring instrument.
2
2
Adjust the settings in small increments and allow the combustion
readings to stabilize before readjusting. When desired adjustments are
complete, check and adjust low fire if necessary.
Gas Valve
To adjust low fire:
Required Tools: 2.5 mm hex wrench and
Combustion analyzer
Start the boiler and observe proper operating
parameters for the system. Set boiler to the
"BNR ON TEST LOW", as described above, to
achieve minimum firing rate of the boiler. Check
combustion readings using the combustion
analyzer. If combustion readings are not in
accordance with Table 3-1, adjust as follows:
Open the front panel of the boiler. Locate the
automatic gas valve. Turn the offset screw,
located in the bottom center of the side of the
High Fire
valve, in the direction indicated on the label to
increase or decrease the gas. Increasing the
gas decreases the O
, while decreasing the gas
2
increases the O
. There will be a slight time
2
delay between the adjustment and the response
Low Fire Adjust
of the CO
/O
measuring instrument. Adjust the
2
2
settings in small increments and allow the
combustion readings to stabilize before
readjusting. When desired adjustments are
complete, check and adjust hi fire if necessary.
43
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