TYPICAL SPECIFICATIONModel CAR-II Constant Airflow Regulators by American ALDES Ventilation Corporation, Bradenton, Florida, shall solely operate on duct pressure and require no external power supply. Each regulator shall be pre-set and factory calibrated requiring no filed adjustment to the airflows as indicated on the schedule, and shall be rated for use in air temperatures ranging from -25°F to 140°F (-32°C to 60°C).
Constant Airflow Regulators shall be capable of maintaining constant airflow within +/-10% of scheduled flow rates (15% for units 50 CFM or less), within the operating range of 0.2 to 0.8 in. w.g. differential pressure, or 0.6 to 2.4 in w.g. on high-pressure models (CAR-II-HP), or 0.1 to 0.42 in. w.g. on low-pressure models (CAR-II-LP). Sound power levels shall not exceed those for each size and CFM rating as scheduled. Regulators shall be provided as an assembly consisting of a 94V-0 UL ABS plastic body housed within a round sleeve for mounting in round duct. Each round sleeve must be fitted with a lip gasket to assure perimeter air tightness with the interior surface of the duct. All regulators must be classified per UL 2043 and carry the UL mark indicating compliance. All Constant Airflow Regulators will require no maintenance and must be warranted for a period of no less than five years. Constant Airflow Regulators shall be installed in tight ducting systems in accordance with all applicable codes and manufacturer’s instructions.
HOW THE CAR-II WORKS
Constant airflow is achieved by controlling the free area
through the device. At minimum static pressure, the aero-wing
is parallel to the air stream. As the static pressure increases,
the aero-wing lifts, thereby reducing the amount of free area
through the regulator. At the same time, the higher static
pressure increases the air velocity resulting in CONSTANT
AIRFLOW. This occurs regardless of pressure differences in
the range of 0.2 to 0.8 in. w.g. (50 to 200 Pa). The air velocity
in the duct is in the range of 60 to 700 ft/min. (0.3 to 3.5 m/s).
Controlling Stack Effect
American ALDES Ventilation Corporation • 4521 19th Street Court East, Suite 104 • Bradenton, FL 34203 – USA
941.351.3441 • 800.255.7749 • 941.351.3442 (fax) • [email protected] • www.aldes.us
© 2013 American ALDES Ventilation Corporation. Reproduction or distribution, in whole or in part, of this document, in any form or by any means, without the express written consent of American ALDES Ventilation Corporation, is strictly prohibited. The information contained within this document is subject to change without prior written notice.
controlling stack effect_application guide_1113
THE PHYSICAL CHALLENGE OF TEST AND BALANCE
Balancing and commissioning of a ventilation riser is usually
considered difficult and tedious. Low airflows through small,
often inaccessible, sidewall-mounted registers located on multiple
floors, is challenging to any test-and-balance contractor. It requires
special instrumentation and many man hours for typical riser
systems. Even with modulating duct openings, the balancer’s
job is compounded by fine-tuning controllers to specified set
points before and after airflow measurements.
In addition to the physical constraints of balancing vertical risers,
the time of year and stage of construction dramatically affect the
measurement readings the contractor will record. This goes back
to stack pressure effects on the system.
THE AMERICAN ALDES CONSTANT AIR REGULATOR
The ultimate solution to ensure proper system balancing and
airflow regulation is the American Aldes CAR-II Constant Airflow
Regulator. The CAR-II is a factory-calibrated passive airflow
regulator that eliminates the need for balancing airflows at the
grilles. It does not require any external power since if automatically
adjusts to the proper airflows in response to duct inlet pressure.
The active control element of the CAR-II is a unique aerofoil. Using
Bernoulli’s Principle, the aero-wing damper lifts in response to
increasing static pressure. This operation regulates the free-area
opening through the control, resulting in maintenance of velocity
and specific airflow setpoints.
Because the CAR-II will maintain the prescribed airflows as it
adjusts to changes in pressure caused by stack effect, it eliminates
over-ventilation caused by the exhaust riser, which saves energy.
The use of CAR-IIs also allows for fan operation at the lowest
pressure level possible without sacrificing airflow performance,
which saves fan energy consumption. Finally, CAR-IIs eliminate
under-ventilation caused by imbalances of the exhaust system,
which protects against poor indoor air quality.
CAR-IIs are employed in thousands of buildings in the United
States and around the world. This well-proven technology was
developed to minimize fan energy use in the late 1970s. Today,
CAR-IIs serve as a simple solution to indoor air quality ventilation
regulation and energy savings. The CAR-II by American Aldes
continues to lead the industry in economical passive airflow control
regulation. Consult the factory, or an American Aldes certified
representative to discuss how CAR-IIs can save money, conserve
energy, and protect any building against poor ventilation control.