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CF2500/CF3500 Burner Manual
Table 2 - Air Tube Capacity Versus Firebox Pressure
Maximum Firing Rate GPH
Model Tube
Firebox
Pressure
(In W.C.)
No
Reserve
Air
10% Turndown
(GPH)
CF2500 &
CF2500A
KP
0.0 25.0 22.5
0.2 24.8 22.3
0.4 24.6 22.3
0.6 24.5 22.1
0.8 24.3 21.9
1.0 24.1 21.7
CF3500A
KM/
KR
0.0 35.0 31.5
0.2 33.5 30.2
0.4 32.0 28.8
0.6 30.2 27.2
0.8 28.8 25.9
1.0 27.1 24.4
Note: 10% turndown indicates suffi cient reserve air to reduce
the CO2 in the fl ue to 90% of its value.
Note: The above ratings may vary 5% due to variations in
actual job conditions.

Dust and Moisture

Mount the Burner

Mount Flange(s) on Air Tube

This section does not apply to burners with welded
fl anges.
Do not install air tube on burner.
For non-pressure fi ring fl ange, refer to Figure 4:
Install gasket (item a) and fl ange (item c). Ignore the
next paragraph.
For pressure-fi ring fl ange, refer to Figure 4: Slide
gasket (item a) onto the air tube, making sure the
top of the air tube is up. Predrill holes in the pressure
fi ring plate (item b) to match the appliance studs.
Slide the pressure fi ring plate (item b) and fl ange
(item c) onto the air tube as shown. Wrap ceramic
fi ber rope (not shown) around the air tube and press
tightly into the inside diameter of the fl ange (item c).
Slide the air tube (item d) into position in the
appliance front. Tighten the fl ange-mounting-stud
nuts. Set the insertion of the air tube so dimension G
is 1/4” nominal.
Pitch the air tube at 2° from horizontal as shown and
secure the fl ange to the air tube.
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Figure 4 – Mount Flange(s) on Air Tube

Stray Light

Protect Against Stray Light

Lockout. Failure to follow

these instructions could cause loss of burner

operation resulting in no heat, an unplanned

process interruption, work stoppage and the

potential for frozen plumbing or other cold

weather property damage.

The control must detect a dark, no-fl ame condition
in order to start the burner or it will hold in the stray
light lockout mode.
Shield the burner view window from direct exposure
to intense light.
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Protect Against Dust and

Moisture

Wet, dusty environments could lead to blocked air

passages, corrosion damage to components, impaired

combustion performance and result in asphyxiation,

explosion or fi re.

This burner is designed for clean, dry installations.
Electrical controls are not protected against rain or sprayed
water.
Keep the installation clear of dust, dirt, corrosive vapors,
and moisture.
Protective covers and more frequent maintenance may be
required.
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Section: Mount the Burner

Protect the Air Tube From

Overheating

Overheating could cause damage to the air tube and

other combustion components leading to equipment

malfunction and impaired combustion performance.

The end of the air tube must not extend into the
combustion chamber unprotected unless it has
been factory-tested and specifi ed by the appliance
manufacturer.
Position the end of the air tube 1/4” back from
fl ush with the refractory inside entry wall to prevent
damage from overheating.
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