Rooftop Unit Control System; Operator Interface - Honeywell AUTOMATIC CONTROL Engineering Manual

ROOFTOP UNIT CONTROL SYSTEM

Figure 6 shows a typical packaged rooftop VAV system
similar to the pervious system but with humidification and
without a return fan. Differential pressure mixed air control is
EA
OA
STATIC
OA OA
PRESSURE
TEMPER- DAMPER
ATURE
RETURN
AND RELIEF
DAMPER

OPERATOR INTERFACE

Modern Building Management Systems (BMS) utilizing
distributed direct digital controllers and personnel computer
based local area networks are installed in many buildings. Full
utilization of a BMS greatly simplifies the operations and
maintenance tasks and provides prompt alert of IAQ problems.
By furnishing quality of information knowledgeable operators
and engineers can easily visualize the system, comprehend the
current status, and determine the nature of any problem.
Operator graphic displays with meaningful real-time
dynamic data displays can enable building operators to
understand how the building is operating. CO 2 , VOC,
airflow, DP, SP, filter, and drain pan alarms can all provide
well suited to roof top applications which usually do not have
sufficient ductwork for flow station outdoor air measurement.
is difficult to ensure air balance in the building.
RA
TEMPERATURE
MA
HEATING COOLING SA
TEMPER-
STAGE VALVE FAN
ATURE
Fig. 6. Typical Rooftop HVAC System.
operator information required to maintain IAQ. Further,
trend logging and dynamic displays can allow the designer
and operator to analyze the building performance
historically or in real-time. And a real-time predictive
maintenance program with status inputs such as filter and
drain pan alarms can be used to prevent degradation of air
quality.
"snapshot" system displays, three dimensional multipoint
dynamic and historical plots, and live video displays of critical
systems are available for a BMS and can be employed in IAQ
application. When these functions are specified, the operator's
value is greatly enhanced by a better understanding of the HVAC
system operation and by real time feedback to adjustments that
are made.
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INDOOR AIR QUALITY FUNDAMENTALS
Without the return fan and with a two position exhaust fan it
RA
SUPPLY FAN
CT
HUMIDIFIER SA
VALVE RELATIVE
HUMIDITY
SA FAN
SA
STATUS
TEMPER-
ATURE
Dynamic graphical operator interfaces providing intuitive
ENGINEERING MANUAL OF AUTOMATION CONTROL
EXHAUST FAN
EXHAUST
FAN
STATUS
SA
SA ROOM AFTER
PRESSURE TEMPER- HOURS
ATURE
M10488