IBC Sl Series Installation & Operating Manual page 75

Combustion fan
Fan plug
High fire (gas:air ratio) adjustment
Gas valve inlet
Inlet gas pressure port
Manifold pressure port
Low fire (offset pressure)
6.3.3.1 Measuring the inlet gas pressure
To perform a gas pressure test, you will need to use a Torx 15 screwdriver and a manometer.
1. Shut off the gas supply. You will be measuring the inlet gas supply from the test port. Do
not perform a test from the manifold gas pressure test port.
2. On the gas valve, loosen the inlet gas pressure test port screw counter-clockwise.
3. Attach the manometer to the inlet gas pressure test port.
4. To measure the inlet gas pressure, switch on the gas supply.
5. When the boiler is operating at high fire, measure the gas pressure. Ensure that you have a
load configured (reset heating, set point, or DHW). This load should be large enough to
allow the boiler to operate at high fire for over 10 minutes.
The gas pressure for natural gas should be around 7" w.c. at high fire and 11" w.c. for
propane.
6. After completing the inlet gas pressure test, switch off the gas supply.
7. Remove the manometer from the inlet gas pressure test port.
8. Tighten the inlet gas pressure test port screw.
9. Switch on the gas supply, and soap test for leaks before returning the boiler to normal
operation.
6.3.3.2 Performing a combustion test and adjustment
The High Fire (gas-air ratio) adjustment screw will have to be adjusted to attain optimum
combustion results whenever fuel conversion is undertaken, however, no mixture adjustment
must be performed unless done by a qualified technician using properly functioning and calibrated
combustion analyzing equipment.
1. Turn off the boiler's external gas shut-off valve.
2. Give the boiler a call for heat.
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6.3.3 Adjusting the gas valve