CEMP-E
TI 811-12
18 August 1998
1/
Proportional control signal to dampers (for direct digital control
implementation).
2/ Minimum OA override of local loop mixed air temperature controls (for supervisory
control
implementation).
(2)
Software I/O requirements. The software requirements are:
(a)
Program inputs.
1/
Changeover dry bulb temperature.
2/
OA dry bulb temperature.
3/
Return air dry bulb temperature.
4/
Equipment constraints.
(b)
Program outputs. Automatic/minimum OA damper control signal.
(3)
Application notes. This program cannot be used where humidity control is required.
5. VENTILATION-RECIRCULATION PROGRAM. The ventilation-recirculation program controls the
operation of the OA dampers when the introduction of OA would impose an additional thermal load during
warm-up or cool down cycles prior to occupancy of the building. This program is particularly useful in
those facilities which maintain environmental conditions (such as electronic equipment installations)
during building unoccupied periods. During unoccupied periods, the OA dampers remain closed. During
building occupied cycles, the OA, return and relief dampers are under normal UMCS control (for direct
digital control implementation) or local loop control (for supervisory control implementation). During
summer cool-down cycle operation, when the OA temperature is cooler than the space temperature, the
OA and exhaust air dampers are opened, and the fans are energized. During winter warm-up cycle
operation, when the OA temperature is warmer than space temperature, the OA and exhaust air dampers
are opened and the fans are energized. Design requirements for this applications program will be
indicated by the letter X adjacent to the program listing on the appropriate database table, as shown in
Chapters 8 and 9.
a. Field hardware requirements. The hardware requirements are:
(1)
UMCS inputs from utility system.
(a)
OA dry bulb temperature - one per facility.
(2)
UMCS outputs to utility system.
(a) Proportional control signal to dampers (for direct digital control
implementation).
(b) Open/close damper override control signal to local loop controls - one per HVAC
system (for supervisory control implementation).
b. Software I/O requirements. The software requirements are:
(1)
Program inputs.
(a)
Day of week/holiday.
(b)
Time of day.
7-5
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