Airwell RT4D 20 [4/56] Technical features continued

Airwell RT4D 60 [4/56] Technical features continued
Page 4
Speed Defrost
In heating mode, particular attention has been given to shorten
the time of defrost and reduce the un-comfort in the building and
improve the overall efficiency. With two circuits, the RT4D allows
one circuit at a time to defrost.
The unique design of the outdoor coil split in two vertical coils,
placed side by side in a V-configuration, ease the defrost of one
circuit without interfering with the heating of the other circuit. The
exhaust fans of the 2-circuits RT4D, are divided in two sections with
distinct air flows, so that each outdoor coil operates independently
from the other.
Four Damper Section
One blower is located in the exhaust air stream, after the outdoor
coil to recover the energy leaving the building.
The air leaving the building is colder than the outdoor air in summer
and warmer in winter. The air leaving the building is used to lower
the condensation temperature in the outdoor coil in summer and
higher the evaporating temperature in winter.
The energy recovered from the building improves the year-round
efficiency of the heat-pump.
The second blower supplies the treated air to the building.
The RT4D is equipped with 4 air dampers (D1, D2, D3 and D4)
designed to handle up to 100% of the nominal air volume.
Fresh air and exhaust air dampers (D2, D3) are mounted in the
opposite way and will open or close to permit enough air to the
outdoor coil .
The danger of uncomfortable over (or under) pressure in the
building is eliminated. This feature insures real energy saving while
controlling at the same time the air changes within the building.
Each one of the 4 counteracting dampers is driven by one
actuator. All of them are connected to the controller.
The damper blades are made of aluminum profile to avoid
corrosion. The blades are geared together to improve the
transmission from the actuator.
The two dampers in the outdoor air (D3 and D4) are hinged.
They can be turned opened on one axis to ease the access to
the inside of the RT4D.
The economizer benefits from the 2 dampers D1and D4,
to utilize the greatest possible quantity of outdoor air (for
free-cooling or free-heating ) without over pressurizing the
building.
The economizer improves the unit efficiency on cooling and
heating.
The dry-bulb economizer is standard. It compares the sensible-
heat of the outdoor air temperature to a reference ambient
temperature setting.
The outdoor air sensor is factory fitted and the discharge air
sensor is field installed (in the supply air duct).
The enthalpy economizer is an option. It compares the quantity
of moisture in the outdoor-air to a reference ambient humidity
setting. Undesired humidity will be detected before it enters the
building.
The night-free-cooling, to pre-cool the building at low cost
during cooler Summer nights (when the outdoor air temperature
is lower than the room setting on un-occupied mode) is
optional.
The minimum position of the outdoor air damper (D3) which
serves the hygienic ventilation of the building, is adjustable at
the controller.
The ambient air quality control (VOC) traces high population
densities in the building and provides sufficient new fresh air
to the occupants. The quality controller is optional. It is not
available with enthalpy economizer.
Dampers D3 and D4 are closed on :
OFF periods to eliminate unwanted outdoor air.
Morning warm-up or start-up until the set-ambient temperature
is satisfied.
Night-set-back modes, to save heating energy.
The smoke detector is located downstream of the filter. This
feature is optional.
Technical Features (continued)
Return air
Return air
Outddoor air
Outddoor air
D1
D2
D3
D4
Supply air blower
Exhaust air blower
Indoor coil
Exhaust air
Evap.
Condenser
Outdoor coil
Room
4-damper double flow - Schematic of principle

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