The OAI feature adds a second pressure independent outside air valve.
New standards practice for HVAC system design, including ANSI/ASHRAE Standard 62.1 — 2010, dictate a minimum amount of ventilation within buildings. Ventilation control has traditionally been done at the central air handling unit;
however, this does not always ensure the minimum ventilation to each zone is maintained. The OAI feature controls outside air to each occupied zone, independently of the primary cooling requirement and therefore prevents over-ventilation that might otherwise occur when relying on sufficient outside air from the primary air system. The OAI feature dual duct inlet design allows the fan powered terminal unit to mix the outside air to the zone with the primary cooling air. The outside air pressure independent air valve provides a constant volume to the zone regardless of thermal conditions. This fixes the outside air requirement for the zone without putting excessive demands for outside air on the primary air handler. In turn, the primary air handler does not have to reset outside air rates for all zones in the building. The first cost of the outside air handler and its associated ductwork can be offset by the savings provided by running smaller outside air volumes for those zones with lower occupancy rates. The OAI feature is perfect for schools. The high occupancy in the classrooms is served without creating excessive loads at the primary air handler serving zones with lower occupancies. Office buildings with conference rooms, kitchen areas and workrooms with copiers can also benefit. When these areas are occupied and require large percentages of outside air, the primary air handler does not have to reset the outside air for all the office spaces in the building. When integrated with a DDC building management system, the amount of outside air can be tracked and logged to ensure 'IAQ' standards for each zone are met and by using occupancy sensors, the outside air volume for individual zones can be reset.
35S-OAI SERIES FEATURES:
- Engineered integral dual duct inlet design is compact and not a bolt on single duct terminal.
- Diamond Flow Sensor located in both primary and outside air inlets.
- Universal access panels for ease maintenance and service.
- Energy efficient PSC fan motor with thermal overload protection.
- Available with electric or hot water supplementary heat.
- Dual air value enclosure for factory mounted DDC controls.
- 3/4" (19), dual density insulation. Exposed edges coated to prevent air erosion. Meets requirements of NFPA 90A and UL 181.
- Adjustable solid state fan speed controller with minimum voltage stop.
- Hinged door on fan controls enclosure
