RTLH RoofTair (Airwell) - Certus

Specification Guide (continued)
special features
Economizer
The rooftop shall be factory assembled with an ECONOMIZER. The
economizer shall have two counteracting dampers linked together to an
actuator, modulating proportionally the volume of outdoor and return air from
0 to 100%.
The blades shall be constructed of galvanized steel with transmission gearwheel.
Retractable weather hood with bird screen shall protect the outdoor
air damper.
Economizer shall have one of the following controls:
• Sensible control using temperature difference (RAT: Return Air
Temperature & OAT : Outdoor Air Temperature).
• Enthalpy control using temperature and humidity sensor to define
enthalpy difference (RAH & OAH).
• Quality control using air quality sensor placed on the return to ensure the
necessary ventilation with more outdoor air to dilute the contaminants
and maintain supply air quality.
Exhaust air blower
An exhaust air blower shall be provided with unit when economizer is fitted.
The exhausted air shall not be short-circuited with the outdoor air intake. The
volume of rejected air shall be at least 25% of the nominal air flow of the unit.
Hot water heating
The hot water coil shall be supplied with a modulating 3-way valve. The coil
shall be mounted on a sliding rail down stream of the DX indoor coil. The
hot water coil shall have the same face area as the indoor coil. A freeze limit
thermostat shall be factory fitted and open the valve, close the outdoor air
damper.
Electric heat
The rooftop shall be factory supplied with an electric heater placed at the
blower discharge in a non-flammable compartment to protect the motor
against radiated heat. The electric elements shall be of stainless steel and
provide 2-stage heats. Manual and automatic reset safety thermostats shall
be factory fitted and wired to the control devices.
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