IBC VX Series, Installation & Operating Manual

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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 on the boiler’s external gas shut-off valve.
2. Give the boiler a call for heat.
3. To run the boiler at high fire, you can set the heat-out value in Test Operation mode to the
maximum MBH for the boiler. To do this, on the controller, go to > Test Operation > In
the Fan Test: Heat Out field, tap 0 MBtu , then enter the maximum MBH.
When the boiler reaches high fire, insert the combustion analyzer test probe into the flue gas
test port. Then verify that the CO
2 reading is within the combustion test targets at Table 11
values.
Figure 44 Flue gas test port
4. Adjust the high fire according to values in Table 11 using a Torx 15 screwdriver. Turn the
screwdriver clockwise no more than a maximum of one full rotation at a time to raise the
CO
2
% (to richen). Turn counter-clockwise no more than a maximum of one full rotation at a
time to lower CO
2
%.
5. Set the heat-out value in Test Operation mode to the minimum MBH for the boiler. To do this,
go to > Test Operation > In the Fan Test: Heat Out field, tap 0 MBtu , then enter the
minimum MBH.
6. Adjust the low fire according to values in Table 11 using a Torx 15 screwdriver. Turn the
screwdriver clockwise to raise the CO
2
% (to richen). Turn counter-clockwise to lower
CO
2
%. Start with ⅛ of a turn until you see the analyzer measure a change then only make
1/16 adjustments. If changing direction on this adjustment you may notice a significant
backlash.
67
6.3.3 Adjusting the gas valve