Heating, Ventilating And Defrosting System - Piper SEMINOLE 2013 Pilot Operating Handbook

PA-44-180, SEMINOLE

7.23 hEATING, VENTILATING AND DEfROSTING SySTEM

HEAT
Heated air for cabin heat and windshield defrosting is provided by a
Janitrol combustion heater located in the forward fuselage (Figure 7-29). Air
from the heater is distributed by a manifold, through ducts along the cabin
floor to outlets at each seat. Heated air from the manifold is also directed
through two ducts to the defroster outlets.
Operation of the combustion heater is controlled by a three-position
switch located on the instrument panel (Figure 7-31) and labeled CABIN
HEAT - FAN. Airflow and temperature are regulated by the three levers
to the right of the switch. The upper lever regulates AIR INTAKE and the
center lever regulates cabin temperature. Cabin comfort can be maintained
as desired through various combinations of lever positions. Passengers have
secondary control over heat output by individually adjustable outlets at each
seat location. The third lever on the instrument panel controls heated airflow to
the windshield defrosters.
For cabin heat, the AIR INTAKE lever on the instrument panel must be
partially or fully open and the three-position switch set to the CABIN HEAT
position. This simultaneously starts fuel flow and ignites the heater. During
ground operation, it also activates the ventilation blower which is integral to
the combustion heater. With instant starting and no need for priming, heat
should be felt within a few seconds. When cabin air reaches the temperature
selected on the cabin temperature lever, the heater cycles automatically to
maintain that temperature.
The combustion heater uses fuel from the airplane fuel system. An electric
fuel pump draws fuel from the left tank at a rate of approximately one-half
gallon per hour. Fuel used for heater operation should be considered when
planning for a flight.
Hours of combustion heater operation can be monitored from an
instrument panel mounted Hobbs meter (Figure 7-31). The meter is located
above and to the right side of the panel, above the heater control switches.
ISSUED: June 5, 2013
SECTION 7
DESCR/OPERATION
REPORT: VB-2307
7-65