Orion System Zoning - Manual (Page 6)

6 Orion Systems
Zoning Design Guide
How Orion Works
As previously discussed, in contrast to the VAV system
the zoning system supplies variable temperature air to
the supply ductwork. The zone dampers modulate and
supply the correct amount of conditioned air to the build-
ing zones and the zone dampers The Polling Device
calculates the heating and cooling requirements for each
zone based on real time information received from each
Zone Controller/Damper. The Polling Device then di-
rects the HVAC unit to provide the appropriate amount
of heating, cooling, and ventilation to satisfy each zone’s
requirements. A static air pressure sensor is used to al-
low the controller to modulate a bypass damper or a
VFD (variable frequency drive) to maintain constant
duct pressure.
The Orion system uses a unique 3 tier approach to con-
trolling the system:
•
Voting Zones
•
System Demand
•
Priority
This 3 tier system works in an integrated fashion to
maintain proper control of the equipment and effective
control of comfort in the zone.
First the zone must initiate a vote to the HVAC unit.
This occurs when a zone becomes more than 1 degree
off setpoint. At this time a vote is placed for heating or
cooling. Next the Polling Device evaluates the total cool-
ing demand or heating demand of the zones served by
the HVAC unit, to determine which requirement is more
critical. Finally, the system looks for any priority con-
ditions, which would take precedence over other zones.
All three of these elements working together provide
accurate and stable control of comfort.
Additional control features are taken into account to
provide very effective control of the system. Some of
these include priority override, supply air temperature
limits, outside air temperature lockouts, and minimum
/maximum position control over the zone dampers.
Substantial savings can be realized using the Orion Zon-
ing system instead of having to install multiple rooftop
units to accommodate multiple zone requirements. The
Orion Zoning system is versatile and can be used with
any packaged roof top unit or split system. It controls a
variety of terminal unit functions including single duct
pressure dependent, pressure independent, series fan ,
parallel fan terminals and electric or hot water reheat.