Gas / Air Ratio Control; Gas Valve Adjustment - Absolute ABS-750 Installation And Operation Manual

Absolute Boilers 750-900-1050

6.3 Gas / air ratio control

The boiler has a pressure differential gas/air ratio control. This gas/air ratio control maintains the correct balance of gas
and air quantities to the burner at a constant level under variable loads. This ensures clean and reliable combustion and
high part load efficiency across the entire load range. Minimum airflow is monitored before a start by an air pressure
sensor.

6.4 Gas valve adjustment

WARNING
Adjustments shall only be performed by a service representative specify trained and certified by Innovative Industrial
Inc. Verify proper operations after servicing.
CAUTION
For high altitude adjustment ( greater than 2,000 feet above sea level) see page # 89
The gas valves are located directly underneath the pre mix blower assembly. The gas valve is mounted on a adjustable
stand that fully supports the gas valve.
Check the combustion using a calibrated combustion analyzer and adjust the fuel-air ratio of the valve being used
according to the procedures below.
To adjust High fire:
Required tools: Flat head screw driver and combustion analyzer.
Start the boiler and observe the proper operating parameters for the system. Set the boiler to High FIRE, to achieve
maximum firing rate of the boiler. Check combustion readings using the combustion analyzer. If combustion readings
are not within the range specified, adjust as follows,
A- Open the front panel of the boiler
B- Locate the Karl Dungs gas valve
C- Adjusts the orifice adjustment screw, located on the downstream side of the gas valve., into the direction indicated
on the sticker to either increase or decrease the flow of natural gas. Increasing the gas flow decreases the
combustion exhaust O2., while decreases the natural gas flow increases the combustion exhaust O2. Note, There
will be a slight delay of 30 seconds from the time the adjustment is made until the gas combustion reads alter. It
is best to make small adjustments of 1 indication marker every 30 seconds to allow the combustion to stabilize
before making further adjustments. When desired adjustments are complete, do a final test and adjust low fire if
necessary.
Absolute Boilers 750-900-1050
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