20
number to reduce CO
2
by 2 percentage points
at a zero smoke level. (Increase O
2
by 3
percentage points at a zero smoke level.)
Example
: Reduce CO
2
from 13.5% to 11.5%,
with zero smoke (or increase O
2
from 2.5% to
5.5%).
A margin of reserve air has been added to
accommodate variable conditions.
Check the breech draft pressure against the
appliance manufacturer’s recommended setting
(typ 0.1” W.C.).
If the breech pressure is higher or lower than
recommended level, adjust the appliance breech
damper to achieve the speci
fi
ed setting. Recheck
the smoke and CO
2
(or O
2
) levels. Adjust burner air
if necessary.
Once all settings are complete and satisfactory,
proceed to
‘Set Low-
fi
re Air’
Section.
Set Low-
fi
re Air
Move the
low-
fi
re hold
switch from the
high
fi
re
position
to the
low
fi
re hold
position.
The damper will return to the
low-
fi
re
air
setting.
Check the smoke and CO
2
(O
2
) levels.
Pull a smoke sample from the
fl
ue.
The sample should be clean (zero smoke level).
Check the CO
2
(O
2
) level:
CO
2
should be at 11 to 12% (O
2
at 5.9 to 4.5%).
If the CO
2
is less than 11% (O
2
more than
5.9%), decrease the air and check the smoke
level.
Operate the burner from
low
fi
re
to
high
fi
re
and
back to verify operation.
Turn the burner off. Wait one or two minutes (for
chamber to clear) and then turn on again to verify
starting characteristics.
Perform limit circuit performance test speci
fi
ed
by appliance manufacturer to verify operation of
burner/appliance combination.
c.
7.
8.
9.
1.
a.
2.
a.
b.
c.
d.
e.
3.
4.
5.
If the burner motor does not start, reset the motor
overload switch (if so equipped) and press the reset
switch of the burner primary control.
Vent the fuel unit as soon as the burner motor starts
rotating. To vent —
Attach a clear plastic tube to the air bleed valve
(
Figure 9 or 10
as applies, item p
).
Place the end of the tube in a container to catch
the oil. Then loosen the fuel unit air vent valve.
Tighten the air vent valve after all air has been
purged.
IF burner stops during venting
—
The burner primary control will lockout if
fl
ame is not established within its time limit.
This is typically 15 seconds for 7505 primary
controls, but may be less for other
fl
ame
supervisory controls.
The burner may lockout several times during
the period needed to purge all the air. To
extend air venting time, press the red reset
button for 1/2 second during the prepurge
cycle to continue purging with 7505 controls.
IF burner stops after
fl
ame established
—
Additional venting is probably required.
Repeat the air venting procedure.
Once
fl
ame is steady, proceed to the
‘Set High-
fi
re
Air’
Section air.
Set High-
fi
re Air
Allow the burner to run at
low
fi
re
until the
appliance has warmed suf
fi
ciently.
Visually check the
fl
ame. The
fl
ame should not be
dark orange or smoky. If the
fl
ame appears to be
smoking, increase the amount of air by readjusting
the damper indicator to a higher number.
Once the appliance has warmed, the
high-
fi
re
setting can be checked and adjusted.
Locate the approximate air adjusting plate setting
for
high
fi
re
in
Table 4
.
Place the
low-
fi
re hold
switch in the
high-
fi
re
position
. The damper motor will begin to rotate
after four seconds.
Use combustion test instruments to adjust the
burner.
Adjust the air by moving the red cam to a lower
number until a trace of smoke is achieved with
CO
2
level as high as possible (lowest possible
O
2
).
Example
: 13.5% CO
2
(2.5% O
2
) with a trace of
smoke.
Increase the air by increasing the red cam
6.
7.
○
○
○
○
-
-
○
-
8.
1.
2.
3.
4.
5.
6.
a.
b.
Section: Prepare the Burner for Start-up
