S
ECTION
7: A
IRPLANE
AND
S
YSTEMS
C
IRRUS
D
ESIGN
E
NVIRONMENTAL
S
YSTEM
SR20
7-62
P/N 11934-005
Distribution
Ventilation and cooling is provided by ducting fresh air from a NACA inlet
on the RH cowl to the mixing chamber located on the lower RH portion of
the firewall. Depending on operating mode and temperature selection, the
air in the mixing chamber is ducted directly into the distribution system or,
if in air conditioning mode (optional), is further cooled as it passes through
the evaporator assembly located under the front passenger seat.
Heating is accomplished by mixing ventilation air from the fresh air inlet
with heated air provided by the heat exchanger in the mixing chamber on
the firewall. From the mixing chamber - which also controls airflow into
the cabin compartment - the conditioned air is forced by ram air pressure
or by blower fan into a distribution manifold mounted to the center, aft side
of the firewall. The distribution manifold uses butterfly valves to control
airflow to the floor and defrost vents. Airflow is ducted directly to all panel
air vents.
Crew panel air vents are located inboard on the RH and LH bolster panels
and on the outboard section of the instrument panel. The crew floor air
vents are mounted to the bottom of each kick plate. The passenger panel air
vents are chest high outlets mounted in the armrests integral to the LH and
RH cabin wall trim panels. The passenger floor air vents are mounted to the
bottom portion of the LH and RH cabin wall trim panels. The windshield
diffuser, located in the glareshield assembly, directs conditioned air to the
base of the windshield.
Heating
Ram air from the NACA inlet flows through the upper cowl and is ducted
to the heat exchanger. The heated air is then routed to the hot air valve,
mounted to the forward side of the firewall, which controls entry of hot air
into the cabin distribution system. When the valve is open, the air flows
into the cabin mixing chamber. When the valve is closed, the heated air
exits into the engine compartment and is exhausted overboard with the
engine cooling airflow. Cabin heat is regulated by controlling the volume of
hot air admitted into the distribution system’s air mixing chamber. The
proportion of heated air to fresh air is accomplished using the temperature
selector mounted on the RH instrument panel.
Cooling
Standard cabin cooling is provided by ram air admitted through the NACA
inlet on the RH cowl to the fresh air valve, mounted to the forward side of
the firewall. When the fresh air valve is open, the air flows into the cabin
mixing chamber. When the fresh air valve is closed, the cooled air exits into
the engine compartment and is exhausted overboard with the engine
cooling airflow.
Reissue A
