Heating, Ventilating And Defrosting System - Piper SENECA III Pilot's Information Manual

SECTION 7
PIPER AIRCRAFT CORPORATION
DESCRIPTION
& OPERATION
PA-34-220T, SENECA
IH
7.25 HEATING, VENTILATING
AND DEFROSTING SYSTEM
Heated
air
for
cabin
heat
and windshield defrosting is provided by a
Janitrol
combustion heater located in the
aft
fuselage behind the
cabin
baggage
compartment
close-out panel (refer
to Figure 7-23). Air from the
heater
is
ducted
forward along the cabin floor to outlets
at each seat and
to
the windshield area.
Operation
of
the
combustion
heater is
controlled by a three-position
switch
located
on
the control
console (Figure 7-25) between
thefront
seats
and labeled FAN, OFF and HEATER. Airflow and temperature
are
regu-
lated by
the two
levers
on
the console. The
right-hand
lever
regulates air
intake
and the left-hand 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 individ-
ually
adjustable
outlets at each
seat
location.
For
cabin
heat, the air intake lever on the heater
control
console
must
be
partially or fully
open
and the three-position switch
set
to the HEATER
position. This simultaneously
starts
fuel flow and ignites the heater;
and,
during
ground
operation,
it also
activates the
ventilation
blower
which is an
integral part of 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, ignition
of
the
heater cycles
automatically to maintain the
selected
temperature.
Two safety
switches activated
by the intake valve and
located aft
of
the heater
unit
prevent both
fan.and heater
operation
when the air intake lever is in the
closed position. A
micro
switch, which
actuates
when
the landing gear is
retracted,
turns
off
the ventilation
blower
so
that in flight the
cabin air
is
circulated by
ram
air pressure
only.
When the
three-position
switch is in
the FAN position during
ground
operation,
the ventilation
fan blows fresh air through the
heater ductwork
for
cabin ventilation and
windshield
defogging when heat is
not
desired.
When the
heater controls are
used either
for
cabin
heat or for ventilation, air
is automatically
ducted to the
windshield area for defrosting.
The flow of defroster
air
to
the
windshield area
can
be increased by the
activation
of a defroster
fan. The fan is
controlled
by a defroster
switch
located
on the control console
between the two front
seats.
REPORT: VB-1110 ISSUED:
JANUARY
8,
1981
30