PIPER
SENECA
II
SERVICE
MANUAL
13-71. EQUIPMENT REQUIRED. (Refer
to
Figure 13-22.)
a.
An improvised stand
to
hold the heater during test. The heater should
be
located far enough
away from any combustible material or atmosphere to avoid hazard. A location should
be
chosen where
exhaust can be dispelled. Do
not
add an excessive extension
to
the heater exhaust.
b. A source
of
fuel capable
of
being regulated
at
seven psi.
c.
The combustion air blower
to
be used with the heater should be used for the test.
d. A 12-volt current supply which may be a
DC
generator with a rheostat, ammeter, and voltmeter
in the line
to
control and indicate the current draw and voltage output.
e. Two water manometers (zero
to
5.0 inch water column) for measuring the pressure in the
ventilating air duct and in the combustion air stream.
f.
A piece
of
duct to be attached
to
the downstream end of the heater.
It
should
have
a minimum
length
of
24 inches and the same diameter
as
the heater being tested. A 2.25 inch diameter orifice should be
centrally located
at
the outlet end. An aperature should be provided for the thermometer and duct switch
and a static tap should be attached
as
shown
in
Figure 13-22.
g.
A thermometer with
500°F
scale.
h. A fuel-pressure gauge.
i.
A con trolled source
of
compressed air for final leakage test.
13-72. OPERATION TEST (ON TEST BENCH). (Refer
to
Figures 13-22 and 13-23.)
a.
Connect the heater
to
the test setup
as
shown
in
Figure 13-22. Make sure the combustion air
blower is mounted securely and that the heater
is
clamped
to
its supporting stand.
b. Insert the duct switch in the sheet metal extension tube
at
the location shown in Figure 13-22.
c.
Connect components and heater
as
outlined in the wiring connection diagram, Figure 13-23. The
power supply switch should be open.
d.
Connect the power source
to
the heater.
e.
Disconnect wire lead from terminal No. 3 on the heater side
of
heater terminal strip
to
prevent
the heater from lighting and close the power source switch to check operation
of
blowers. The combustion
air blower and ventilating air blower should operate at full speed with no blower wheel interference.
If
either blower fails
to
run, locate and correct the trouble before proceeding with the test.
f.
Connect a voltmeter from open side
of
combustion air pressure switch terminal
to
ground
to
determine if the switch
is
closed, which would be indicated
by
a full voltage reading on the meter.
If
a full
voltage reading is
not
obtained, the combustion air supply is either inadequate or the switch
is
defective or
improperly adjusted. Make necessary corrections.
g.
Observe the manometer connected
to
the ventilating air pressure tap, which should show a
reading
of
1.1
inches
of
water (minimum) at rated voltage.
h. Observe the manometer connected
to
the combustion air tube tap, which should show a reading
of
1.5 inches
of
water (minimum) at rated voltage.
i.
Open the power supply switch and reconnect the terminal lead disconnected in preceding Step
e.
j.
Close the power supply switch and turn on the fuel supply. The heater should light within
five
seconds (may require slightly longer for air
to
be purged from fuel lines on the first trial).
k. Observe operation
of
duct switch, which should control heater operation according
to
the switch
setting.
1.
If
the duct switch fails
to
control the temperature according
to
the setting, place the control lever
in high
"H"
position and notice the control variation. A high reading
of
250° F ± 10° should be obtained
(reading will vary in different applications).
Reissued:
10/11/79
HEATING
AND
VENTILATING
SYSTEM
2L7
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