Heating And Ventilating System Description; Janitrol Heater Operation - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
SECTION XIII
HEATING AND VENTILATING SYSTEM
13-1. INTRODUCTION. This section contains information for the operation, service and overhaul of the
combustion heater and combustion air blower (used with the heater). The instructions are organized so that
the mechanic can refer to: Description and Principles of Operation, for a basic understanding of the
system; Troubleshooting, for a methodical approach in locating the difficulty; Corrective Maintenance, for
the removal, repair and installation of components; and adjustments and tests, for the operation of the
repaired system.
13-2. DESCRIPTION AND PRINCIPLES OF OPERATION. The flow of air for heating and defrosting is
taken through an inlet in the lower right side of the airplane nose section and directed to a Janitrol heater
located in the right side of the nose section. From the heater, air for defrosting is directed through outlets
located on the instrument panel cover, while air for cabin heat and fresh air is delivered through outlets on
the forward cabin bulkhead and grills located in the cabin side panel next to the floor. These functions are
controlled by a heater switch and control levers along the lower right side of the instrument panel.
The heater is protected from overheating by a heat limit switch. If the heater temperature reached a
predetermined setting. the limit switch opens and the heater becomes inoperative. This is indicated by the
illumination of the OVER TEMP warning light in the annunciator panel. The OVER TEMP light will stay on
until the temperature drops below the predetermined limit. The heater can be reset using the START/RESET
button under the heater switch after the OVER TEMP light goes out.
An additional scoop mounted on the bottom of the airplane draws fresh air into the cabin through
individual vents at each seat. Each vent is adjustable for the desired air flow. A cabin exhaust outlet is
located in the raised floor panel of the aft cabin area. The exhaust scoop is located in the lower, center
section of the fuselage. in line with the cabin door. This exhaust scoop is controlled by a push-pull knob on
the lower right side of the instrument panel. A ventilating fan for this outlet is available as optional
equipment.
13-3. JANITROL HEATER.
13-4. TROUBLESHOOTING. Troubles peculiar to the heating and ventilating system are listed in Table
XIII-I at the end of this section, along with their probable cause and suggested remedies.
13-5. HEATER OPERATION. The 50,000 B.T.U. Janitrol heater is controlled by a three position switch
located on the lower right side of the instrument panel, labeled FAN, OFF and HEAT. The FAN position
will operate the vent blower only and may be used for cabin ventilation on the ground or windshield
defogging when heat is not desired. When heat is desired the heater switch must be turned to the HEAT
position. This will start fuel flow and ignite the burner simultaneously.
The heater uses gasoline from either right fuel tank when the fuel crossfeed is off, and from all tanks
when the crossfeed is on.
The control levers along the bottom of the instrument panel control air flow and temperature. The
second lever from the right regulates air flowing to the cockpit and cabin through the heater system. The
left lever is connected to an adjustable thermostat which makes it possible to select the desired temperature
of heated air and the second lever from the left is the defroster control.
Reissued: 9/23/80
HEATING AND VENTILATING SYSTEM
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