TM 5-4520-208-15
(8) Install capillary tube shield (11) on
(2) Inspect valves and block for evidence
casing and secure with three screws
of leaking and damage. Check capil-
(8), lockwashers (9), and nuts (10).
lary tubes and sensing elements for
(9) Position duct adapter assembly (4) in
breaks, cracks, or other damage. Re-
casing and secure with four screws
place complete unit if damaged.
(5), lockwashers (6), and nuts (7).
d. Installation
(10) Install sensing elements, (1 through 3)
Note. Steps (1) and (2) below pertain only to the
in clips (12 and 13) in duct adapter.
Model BT400-40 heater.
(11) Install control box to fuel controls.
(1) Position the block on bulkhead and
Refer to paragraph 97 for BT400-40
secure with two screws (38, fig. 34)
and paragraph 98 for BT400-40-1.
and lockwashers (87).
100. Heater Control Valves and Block
(2) Position bracket (23) over valves. In-
a. General The two heater control valves
stall nut (21) on temperature selector
are secured to the fuel block and the block is
valve. Install temperature selector gear
mounted on the bulkhead, The fuel control
(11) in bracket.
valve turns the burner on and off and the
Note. Steps (3) and (4) below pertain
temperature selector valve selects and regulates
only to the Model BT400-40-1 heaters.
the discharge air temperature
(3) Position the block on bulkhead and
b. Removal.
secure with two screws (39, fig. 37)
(1) Remove heater control tube and hose
and lockwashers (38).
assemblies. Refer to paragraph 97 for
(4) Position bracket (23) over valve. In-
BT400-40 and paragraph 98 for
stall temperature selector gear (11) in
BT400-40-1.
bracket.
(2) Remove temperature gage (para 99).
(5) Insert sensing elements (1 and 2, fig.
Withdraw sensing elements (1 and 2,
ture gage (para 99).
casing.
(6) Install heater control hose and tubs
Note. Steps (8) and (4) below pertain
assemblies. Refer to paragraph 97 for
only to the Model BT400-40 heater.
BT400-40 and paragraph 98 for BT-
(3) Remove temperature selector gear (11,
40040-1.
e. Valve Test and Adjustment. If the tem-
temperature selector valve and remove
perature selector valve is not coordinated with
bracket (23) from valves.
its knob, adj ust valve as-follows:
(4) Remove two screws (38) and lock-
( l ) Test fuel pump pressure and adjust
washers (37) and remove block, with
if necessary. Refer to paragraph 86 for
attached valves, from heater.
BT400-40 or paragraph 90 for BT-
Note. Steps (5) and (6) below pertain
400-40-1.
only to the Model BT400-40-1 heater.
(2) Open the control box cover (fig. 11).
(5) Remove temperature selector gear (11,
(3) Turn temperature selector valve knob
clockwise as far as it will go until the
temperature selector valve and remove
pointer on the temperature indicator
bracket (23) from valves.
knob is against the pin. If pointer
(6) Remove two screws (39) and lock-
does not travel far enough to reach
washers (38) and remove block, with
pin, loosen setscrew securing knob and
attached valves, from heater.
move pointer to pin and secure set-
c. Cleaning and Inspection.
screw, provided temperature selector
(1) Clean exterior of Mock and valves
valve knob is at maximum clockwise
with an approved cleaning solvent and
position.
dry thoroughly.
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