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TranSystems Corporation - LGM Construction

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501070099 Federal Express Oakland Sort Expansion Issued for Bid 10/11<br />

operation a fan failure alarm will be annunciated, the unit will stop, requiring a manual<br />

reset.<br />

I. Space Pressure Control (Statitrac):<br />

1. When the programmed exhaust enable setpoint is reached, the exhaust fan control is<br />

activated. If the space pressure is equal to the programmed space pressure setpoint the<br />

exhaust fan and dampers will be inactive. If the space pressure increases above the<br />

programmed space pressure setpoint the controller will turn on the exhaust fan and<br />

modulate the exhaust fan VFD/damper to relieve building pressure. When the space<br />

pressure decreases to within the programmed space pressure setpoint, the exhaust fan<br />

VFD/damper position will remain constant. When the space pressure equals the<br />

programmed space pressure setpoint, the controller will modulate the relief air dampers<br />

until building pressure returns to the programmed space pressure setpoint. If the space<br />

pressure falls below the programmed space pressure setpoint, the controller will<br />

deactivate the exhaust fan VFD/dampers. If the economizer damper closes to a point<br />

below the programmed exhaust enabled setpoint, the controller will assume an inactive<br />

state.<br />

J. Exhaust Fan Status:<br />

1. A differential pressure switch will monitor the differential pressure across the fan. If the<br />

switch does not open within 40 seconds after a request for fan operation a fan failure<br />

alarm will be annunciated, the unit will stop, requiring a manual reset.<br />

K. Filter Status:<br />

1. A differential pressure switch will monitor the differential pressure across the filter when<br />

the fan is running. If the switch closes for 2 minutes after a request for fan operation a<br />

dirty filter alarm will be annunciated.<br />

4.3 VAV BOX WITH PARALLEL FAN, HOT WATER HEAT, AND DDC CONTROLLER (DIRECT DIGITAL<br />

CONTROL)<br />

A. Building Automation System Interface:<br />

1. The Building Automation System (BAS) will send the controller Occupied and Unoccupied<br />

commands. The BAS may also send a Heat/Cool mode, priority shutdown commands,<br />

space temperature and/or space temperature setpoint. If a BAS is not present, or<br />

communication is lost with the BAS, the controller will operate using its local setpoints.<br />

B. Heat/Cool Mode:<br />

1. The Heat/Cool mode will be set by a communicated value or automatically by the VAV. In<br />

standalone or auto mode the VAV will compare the primary air temperature with the<br />

configured auto changeover setpoint to determine if the air is "hot" or "cold". Heating<br />

mode will command the VAV to heat only; it implies the primary air temperature is hot.<br />

Cooling mode commands the VAV to cool only; it implies the primary air temperature is<br />

cold.<br />

C. Heat/Cool Setpoint:<br />

DIRECT DIGITAL CONTROL SYSTEM 15900-24

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