Reznor SFT Unit Installation Manual - Manual (Page 20)

Form RZ -NA-I-SFT, Mfg No. 173474 (Rev 6), Page 19
Figure 14 - Location of Controls on a Model SFT45-300 (with the door open, all of the
controls except the limit control are visible in one compartment)
Limit Control - Sizes
100-300 (located in heat
exchanger compartment)
Combustion Air Collar
(flex hose removed for clarity)
Flame Rollout
Switch - Sizes 45-75
(located on the burner
box cover “behind”
the collar; disconnect
hose to access)
Limit Control Location -
Sizes 45-75 (located in heat
exchanger compartment;
remove louvers to access)
Burner/Manifold
Assembly
Ignitor
Ignition
Control
Module
Flow Sensor (for
tubing connection
to the pressure switch)
Inlet
Collar
Fan
Motor
Venter Outlet
(Flue) Collar
Venter Motor and
Wheel Assembly
Pressure
Switch
Transformer
Flame Sensor
Gas Valve (When lighting,
turn gas control knob or lever
“OFF”; wait five minutes; turn
gas control knob or lever “ON”)
Terminal
Block
7. Remove the small manifold seal plate and cover plate. Remove the
burner box cover. The burner rack assembly is visible.
8. At the bottom of the burner rack assembly, remove the nut that
secures the burner rack to the bolt welded to the burner box bottom.
At the top of the burner rack assembly, remove the bolt that at-
taches the burner rack assembly to the bracket. Lift the burner rack/
manifold assembly upward (to clear the locating weldpins) and pull
the assembly out of the heater.
Clean the Burners (requires a wire brush,
cleaning cloth, and an automotive type aerosol
degreaser or refrigerant coil cleaner)
CAUTION: Use of eye protection is recommended.
Excessive dirt buildup on and inside the ports on the burner could
cause fuel gas to spill out of the back of the burner tube. Fuel gas
spilling out of the back of the burner tube will cause gas odor inside
the building, and if not corrected, could eventually cause a fire/explo-
sion hazard. To prevent fuel gas spilling from the back of the burners,
check the burner ports at least annually and clean if necessary. Remove
any soot deposits from the burner with a wire brush. Clean the ports
with an aerosol degreaser and/or compressed air. Wipe the inside of the
burner tube clean. (Cleaning the burner with an aerosol degreaser is
highly recommended as the degreaser will retard future buildup of dirt.)
Inspect the cleaned burner for any damage or deterioration. If the burner
has any damage or signs of deterioration, replace it.
Re-assemble the heater and test for proper operation.
20. Burner Orifices
Heaters are shipped with orifices of proper size and type for gas and
altitude specified on the order. When ordering replacement orifices,
give BTUH content, specific gravity of gas, and altitude, as well as the
model and serial number of the heater.
21. Heat Exchanger
The outside of the tubular heat exchanger can be cleaned from the
front of the heater with an air hose and/or a brush. Remove all accumu-
lated dust and grease deposits.
CAUTION: Eye protection is recommended.
The inner surfaces of the heat exchanger can be reached for cleaning
with the burner, turbulators and venter assembly removed (See Para-
graph 18 and Figures 13 and 14). Turbulators are "wavy" strips of metal
that extend into the heat exchanger tubes. Remove and clean the
turbulators (save the screws). Clean the inside of the tubes with a long
furnace brush or a heavy wire to which steel wool has been attached.
Brush inside each heat exchanger tube until all foreign material is re-
moved. A flashlight is helpful in examining the inside of the tubes.
Slide the clean turbulator strips back into the tubes and re-attach using
the screws removed.
22. Ignition System
To access the ignition system, follow Steps 1-3 in Paragraph 19.
Ignitor - Refer to Figure 14 and locate the ignitor (on the side of the
burner rack). Disconnect the wire; remove the screw and the ignitor.
Clean the ignitor assembly with an emery cloth.
Spark gap must be maintained to 1/8". See Figure 13.
Figure 13 - Ignitor Assembly .74
1.275
7/16
.125 ±.015 Spark Gap
5/32
Spark Gap
Measurement