Operational Test - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
13-49. EQUIPMENT REQUIRED. (Refer to Figure 13-19.)
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 7.5 ± .5 psi.
c. The combustion air blower to be used with the heater should be used for the test.
d. A 28 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 13-19.
g. A thermometer with 500
°
F scale.
h. A fuel-pressure gauge.
i.
A controlled source of compressed air for final leakage test.
13-50. OPERATIONAL TEST. (Refer to Figures 13-19 or 13-20.)
a. Connect the heater to the test setup as shown in Figure 13-19. 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 13-19.
c. Connect components and heater as outlined in the wiring connection diagram. Figure 13-20. The
power supply switch should be open.
d. - Connect the power source to the heater.
e. Disconnect wire lead from terminal "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, either the combustion air supply is 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).
m. Connect a jumper across the terminals of the duct switch to make it inoperative and observe
action of the cycling switch. The cycling switch should cycle to control the outlet air temperature at
approximately 250°F (nominal). This is a function of ambient temperature and air flow conditions. If
operation is within a range of 190°F to 290
°
F, the switch is operating normally. If the switch is out of
range it can be reset in the same manner as described for the duct switch, except that no control lever or
indicator stop are used. If adjustment fails to restore proper temperature range, replace the switch.
Reissued: 9/23/80
4 C20
HEATING AND VENTILATING SYSTEM