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How To Check Gas Combustion
Setting procedure for high firing
Unscrew the EC adopter cap on vent collar (see to above diagram) and connect the flue gas analyzer.
Set to full load:
with the unit at 130°F or higher, force the unit into high fire by opening demand of at least 7
GPM water flow rate.
Wait 10 seconds for modulation to stabilize with the full-load fan speed, measure the O
2
/CO
2
percentage and
compare this to the values in table 1.
Check the flame through the sight glass which should be stable with a regular flame distribution.
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Setting procedure for low firing
Set to low load:
Turn dipswitch #3 in group 3 to ON and throttle demand down to no more than 2 GPM water flow rate.
Wait at least 10 seconds for modulation to stabilize with the low-load fan speed, measure the O
2
/CO
2
percentage
and compare this to values in table 1.
If the values are not in accordance with the table then correct the gas/air ratio valve using the adjusting screw A
on gas valve.
If the value is too low turn the adjusting screw A clockwise; this increases the gas rate - if the value is too high
turn the screw anti clockwise which decrease the gas rate.
Flip dipswitch #3 in group 3 to OFF.
Cold flush the unit and let it take itself through at least 1 cycle on standby fire for boot up diagnostics.
Check the flame through the sight glass which should be stable with a regular flame distribution.
Reinstall the flue stack cap when finished testing.
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Only make small adjustments of the adjusting screw maximum 1/8 turns at a time when setting O
2
/CO
2
.
Ensure that the analyzing probe has a gas tight seal in the sampling point with the probe end in the centre of the flue duct.
Repeat the “test at high firing” and “test at low firing” as often as necessary until the correct values are achieved
without further adjustments.
NOTICE
!
!
HOW TO CHECK GAS SUPPLY PRESSURE
Turn off power source and turn off gas supply to the unit.
Remove the front cover from the unit.
Loosen the gas supply pressure test port screw and connect manometer to this port; turn on the gas to the
water heater.
Turn the water heater on and open multiple taps to force unit into high fire; check gas supply pressure at the
test port with a manometer with unit in high fire.
1.
2.
3.
4.
NOTICE
!
!
Manifold Gas Pressure should be adjusted on low and high fire.
If gas supply pressure drops below 3.5" WC unit will not have enough gas volume for max fire!
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WARNING
!
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