1 Remove six nuts (1 and 2) and flat
washers (3) from studs on burner cup and stud
assembly (14). Remove burner cup from plate and
bushing assembly (6).
2 Remove screw (13) and pull off fuel
vaporizer shield (12), and washers (10 and 11).
Detach yarn wick (5) from with support in plate and
bushing assembly (4). Remove fuel vaporizer (9),
retaining washer (8), notched washer (6), slotted
washer (7), and second notched washer (6).
(9) Heat exchanger (fig. 3-10.2).
(a) If the heat exchanger (15) is being
removed for heater overhaul, remove the following
components to facilitate cleaning of the heater
1 Ignition control ((7) above. )
2 Fuel control valve ((6) above).
3 Overheat switch ((5) above).
4 Electrical inlet assembly ((2) above).
(b) Remove burner assembly ((8) above.
(c) Remove the flame detector switch ((4)
(d) Disconnect ground lead assembly (12, fig.
3-10.2) from heat exchanger (15) by removing at-
taching screw (11).
(e) Remove four screws (34) holding together
the seam of the heater housing (28). Spread heater
housing and slide out heat exchanger (15).
(f) Remove the ground lead (12) from the
heater housing (28) by removing the nut (14) and
lockwasher ( 13).
(g) If the grommet (33) is worn or damaged,
remove it from the heater housing.
Be careful when using cleaning solutions
and solvents. Do not expose skin to
solvents or inhale their vapors. Many
cleaning agents are toxic, and contact
with them or their vapors may cause
illness or death. Wear protective clothing
and devices, and ensure adequate ven-
tilation while using cleaning agents.
a. Clean dirt and foreign matter from all exterior
metal parts with drycleaning solvent or mineral
spirits paint thinner and dry with compressed air.
b. Clean air inlet hose and rubber seals in a mild
soap solution, rinse and dry.
c. Clean the fuel filter in the inlet line to prevent
the collection of moisture and the formation of ice
during cold weather. Follow the manufacturers
Do not attempt to operate the heater
without a fuel filter, or with the fuel filter
element removed. The filter element
prevents the entry of dirt, ice crystals,
wax, and other contaminants which can
easily plug the tiny orifices in the fuel
d. Clean blower housing, ventilating blower
wheel, combustion blower wheel, secondary blower
cover assembly, motor mounting brackets, and ex-
terior of motor with a cloth dampened with cleaning
e. Clean the burner and heat exchanger. The bur-
ner has been designed to eliminate excessive buildup
of carbon and other deposits within the combustion
chamber. However, buildup can occur under
unusual operating conditions or if other components
are malfunctioning. A minor carbon buildup may be
removed by operating the heater at near maximum
voltabe and restricting outlet airflow to maintain
the temperature of the heat exchanger at or near an
overheat condition. The operate the heater on LO
long enough to permit the excess combustion air to
burn out soot and carbon. Repeat this cycle several
(1) If this procedure faills to clean the heat ex-
changer enough to restore performance, or if the
burner or heat exchanger require further service,
remove the heat exchanger as described in
paragraph 3-33c(9), and then remove as much of
this deposit as possible, using a flexible scraper.
Remove combustion residue from inside heat ex-
changer by soaking this assembly in a 20 percent by
weight solution of ammonium acetate at a tem-
perature of 1800 F., for a period of 5 to 10 hours.
Flush out exchanger with water after cleaning, and
dry with compressed air.
(2) For units which have been burning other
types of fuel, such as diesel fuel, JP-4, etc., water
should be used to flush the heat exchanger. Use
compressed air to dry the inside of the heat ex-
changer and remove all traces of water before heat
exchanger is reinstalled in the heater.
f. Wipe all non-metallic parts of fuel control valve
with a clean, dry cloth. Clean metallic parts except
the orifice plate with a cloth dampened with
cleaning solvent. Take care not to saturate electrical
windings or insulation with solvent. Dry all parts
thoroughly. Clean orifice plate holes and orifice
plate with solvent and compressed air. Inspect for
cleanliness with a magnifier.
Do not force any tool or object through
the orifice plate openings. The slightest
distortion in these calibrated holes will
change the factory calibrated
g. To clean the flame detector
rate of fuel
switch, refer to