Specifications

7-78 Information Manual
Section 7 Cirrus Design
Airplane Description SR20
Environmental System
Cabin heating and ventilation is accomplished by supplying
conditioned air for heating and windshield defrost and fresh air for
ventilation. The basic environmental system consists of a heater muff
(heat exchanger) around the right engine exhaust muffler, fresh air
inlets(s), hot air valve, distribution manifold, air ducting for distribution
windshield diffuser, vent outlets, and required actuators for selecting
temperature and flow. Serials 1637 and subsequent; An optional 3-
speed blower fan is available to supplement airflow when ram air may
be inadequate such as during ground operation.
Description and Operation - Serials 1005 through 1636
Ventilation air is provided by ducting fresh air from air inlets, located in
each wing leading edge, to eyeball outlets for each occupant. Each
occupant can direct the fresh air flow by positioning the nozzle or
control flow rate from 'off' to maximum by rotating the nozzle.
Heating is accomplished by mixing ventilation air from the fresh air
inlets with heated air from the heat exchanger and then distributing the
'conditioned' air to the occupants and/or the windshield diffuser. Air for
heating is supplied by an inlet in the engine compartment to a muff-
type heat exchanger surrounding the right engine exhaust muffler.
This heated air is allowed to mix with fresh air from the wing root air
inlets in the air mixing plenum behind the instrument panel. The
proportion of heated to fresh air is pilot controllable. The mixed
(conditioned) air is then directed to the passenger outlets and/or to the
windshield diffuser. Conditioned air outlets for the forward occupants
are directionally controllable and are located beneath the instrument
panel at each position at knee level. Outlets for the rear occupants are
at floor level.
The temperature, volume, and flow selection are regulated by
manipulation of the cabin temperature and cabin air selector knobs on
the lower right side of the instrument panel.
March 2010